Pembangkitan ARMA Time Series

Dinda Khamila Nurfatimah

2023-09-21

White Noise

White noise dibangkitkan dari suatu peubah acak, umumnya peubah acak normal.

set.seed(035)
wn <- rnorm(300)
ts.plot(wn)

Dapat terlihat bahwa white noise tidak memiliki autokorelasi dari ACF. Perhatikan bahwa lag ke-0 adalah korelasi observasi ke-t dengan dirinya sendiri. Nilai korelasi tersebut pasti 1. Sebagai alternatif, lag pertama di plot ACF dapat ditetapkan sebagai 1 (alih-alih 0) dengan menambahkan argumen xlim(1, lag akhir). Plot tersebut dapat disandingkan bersamaan dengan membuat matriks \(1 \times 2\) dengan par(mfrow = c(1,2)).

par(mfrow = c(1, 2)) 
acf(wn)
acf(wn, xlim = c(1, 20))

Proses MA

Proses MA dapat dituliskan sebagai berikut:

\[ y_{t} = c + e_t + \theta_{1}e_{t-1} + \theta_{2}e_{t-2} + \dots + \theta_{q}e_{t-q} = c+{e_t+\sum_{i=1}^p \theta_ie_{t-i}} \] Terlihat bahwa \(e_t\), atau white noise, berperan penting dalam pembangkitan proses MA.

Pembangkitan Proses MA(2)

Akan dicoba membangkitkan proses MA, yaitu MA(2) dengan \(\theta1 = 0.4\) dan \(\theta2 = 0.6\) sebanyak 300 observasi dan \(c=0\). Karena diperlukan satu nilai awal untuk \(e_{t-1}\) dan \(e_{t-2}\), masukkan nilai pertama white noise sebagai nilai awal tersebut.

set.seed(035)
ma <- wn[c(1,2)]

Nilai-nilai selanjutnya dapat dicari melalui loop. Bentuk loop dapat dilihat dari rumus MA(2) yang hendak dibangkitkan:

\[ y_t = e_t-0.4e_{t-1}-0.6e_{t-2} \]

for(i in 3:300){
   ma[i] <- wn[i] + 0.4 * wn[i - 1]+ 0.6 * wn[i - 2]
}
ma
##   [1]  1.065125327  0.132881183  0.658183657  0.021134760  3.299420916
##   [6]  0.915231810  2.256101722 -0.633709544  1.212692091  0.488247563
##  [11]  1.365917354  0.859402939 -0.283312528 -0.541257282 -2.570059470
##  [16] -2.842772162 -0.992370374 -1.067240744  2.218516529  2.200945279
##  [21]  2.456432824  2.234504393  1.795219724  2.251167470  0.790990469
##  [26]  1.215940621  0.526099293  1.094760371  1.080962605  0.908300966
##  [31]  1.652803499  1.790913751  2.372726341  0.977329459 -0.011604417
##  [36]  2.056545611  0.680957663  0.901810835  1.465150702 -0.401660786
##  [41]  0.319160465 -0.522727520 -1.385340145 -1.252614832  0.060156387
##  [46]  0.716966475  0.894508358  1.499279489  0.469600491  1.402106532
##  [51]  0.485686038  1.584133220 -0.450447425 -1.134048977 -0.870574767
##  [56] -1.499551006  1.219248831 -1.084224277  0.025365132 -1.345499887
##  [61]  1.256230369  0.885180465  0.928511990 -0.615893983 -0.629149599
##  [66]  2.333284252  1.260046662  0.928009646  0.300440456 -1.609279361
##  [71] -2.243711296 -1.228093288 -0.384008230  2.222052781  1.366946810
##  [76]  0.286202500 -0.437222316  0.251184461  0.177087208  0.875363006
##  [81]  0.451368246 -0.956924380 -1.007689595 -2.619731719 -0.971496099
##  [86]  0.016829578  0.261893053  0.721130841  0.072592286  0.729277777
##  [91]  0.252451354  0.368767403  0.675968503  0.852165073  0.012702662
##  [96]  1.669574565  1.868642026  0.915469178  0.359566884 -2.382471996
## [101] -1.268563372 -2.236629932  0.851566374  1.054256325  1.839758922
## [106]  1.089107790  2.282569970  0.501388394  2.310241027  1.924577740
## [111]  0.701628854  1.572163933 -0.811353906  1.491858309  0.024586469
## [116]  1.112575616 -0.571601276  0.377668248 -0.188704184  2.200551532
## [121]  0.137980542  0.950017590 -2.185559323  1.929037466 -0.806797583
## [126] -0.380090545 -1.144726418  0.324724378 -0.042361431  0.262863488
## [131] -2.286748789 -1.897223008 -0.380051401  0.816209921  2.132221753
## [136]  0.261903736  2.475658531  1.600373208  1.304524934  1.819312966
## [141]  1.362641279 -0.413939576  1.261613549  0.050621698  1.056754925
## [146] -0.986731556 -1.222474981 -0.376638636  1.363648342  2.452450632
## [151]  0.754805726  0.995028968  1.576494524  0.252185400  1.371836640
## [156] -0.192063167  1.124324950  1.373842963  0.161530570 -0.548495611
## [161]  0.122079347 -0.162928307  0.869627949  1.645302830 -0.133512418
## [166]  0.577205198  1.332200135  2.314074616  2.541704734  2.329764342
## [171]  0.760551363  1.260166357 -0.545679568 -0.526906104  0.141787476
## [176] -0.865162719  0.776325959 -0.800867390 -0.892046480 -0.198269829
## [181]  0.391609515 -0.323115699  1.411984335  1.539053907  1.726604278
## [186]  2.101460674  0.952816063  0.630389142 -0.434972955  0.284244921
## [191] -0.629639814 -0.326646935  0.071838968  0.089770764  2.391026520
## [196]  0.344158345  0.726821474 -0.426357782  0.673665279  0.476988095
## [201]  1.031459004 -0.824513344 -0.296015791 -1.270447231  0.741566980
## [206] -1.917525859  2.152745644 -0.934229115  0.986361102 -2.327510614
## [211] -0.836100979 -2.203163018  1.251274713 -0.483100429  0.405541344
## [216] -1.046801129 -0.118265714 -1.479388762 -0.972990734 -1.654317862
## [221] -0.369158859  1.188879940  0.758165612  0.004675097 -0.842823443
## [226]  0.789932300 -0.806046838  0.823141063 -1.638547001 -0.956585019
## [231] -3.511118437  0.160155860 -0.352221471  2.080835571  1.155445559
## [236]  0.007319216 -0.349601438 -1.389952187 -0.480352506 -0.374425649
## [241]  1.536508308  2.946040765  2.058586017  1.043034785 -0.514395852
## [246]  0.448597128 -0.107166162 -0.901895755 -0.643922756 -1.073635485
## [251] -1.848150055 -0.975969799 -1.018716345 -0.046728256 -0.457365043
## [256]  0.290596707 -0.817736130 -0.285379062 -1.197053507 -0.809829780
## [261] -0.284903059  1.427407937  2.072450303  2.578961105  0.990888560
## [266]  0.130744460 -1.055302300 -0.349721522  0.489784548  0.652814461
## [271]  0.864882450 -1.406581322  0.300966391  0.964790201  1.260471246
## [276]  1.745385800  0.068547273  3.790009529  0.959858473  2.336401436
## [281] -1.004590961 -1.634457108 -0.245794766 -1.413568572 -0.134170647
## [286] -0.816912736  0.107330937 -0.639551099 -0.525883926 -1.055692764
## [291] -0.158199423 -0.107872805 -0.227482501  0.463732156 -0.382036141
## [296]  0.326448357  0.727266022  1.184649221  2.168488530  1.460507679

Selain menggunakan cara di atas, pembangkitan proses MA(2) dapat dilakukan dengan fungsi arima.sim() sebagai berikut.

ma2 <- arima.sim(list(order=c(0,0,2), ma=c(0.4,0.6)), n=300)
ma2
## Time Series:
## Start = 1 
## End = 300 
## Frequency = 1 
##   [1]  0.658183657  0.021134760  3.299420916  0.915231810  2.256101722
##   [6] -0.633709544  1.212692091  0.488247563  1.365917354  0.859402939
##  [11] -0.283312528 -0.541257282 -2.570059470 -2.842772162 -0.992370374
##  [16] -1.067240744  2.218516529  2.200945279  2.456432824  2.234504393
##  [21]  1.795219724  2.251167470  0.790990469  1.215940621  0.526099293
##  [26]  1.094760371  1.080962605  0.908300966  1.652803499  1.790913751
##  [31]  2.372726341  0.977329459 -0.011604417  2.056545611  0.680957663
##  [36]  0.901810835  1.465150702 -0.401660786  0.319160465 -0.522727520
##  [41] -1.385340145 -1.252614832  0.060156387  0.716966475  0.894508358
##  [46]  1.499279489  0.469600491  1.402106532  0.485686038  1.584133220
##  [51] -0.450447425 -1.134048977 -0.870574767 -1.499551006  1.219248831
##  [56] -1.084224277  0.025365132 -1.345499887  1.256230369  0.885180465
##  [61]  0.928511990 -0.615893983 -0.629149599  2.333284252  1.260046662
##  [66]  0.928009646  0.300440456 -1.609279361 -2.243711296 -1.228093288
##  [71] -0.384008230  2.222052781  1.366946810  0.286202500 -0.437222316
##  [76]  0.251184461  0.177087208  0.875363006  0.451368246 -0.956924380
##  [81] -1.007689595 -2.619731719 -0.971496099  0.016829578  0.261893053
##  [86]  0.721130841  0.072592286  0.729277777  0.252451354  0.368767403
##  [91]  0.675968503  0.852165073  0.012702662  1.669574565  1.868642026
##  [96]  0.915469178  0.359566884 -2.382471996 -1.268563372 -2.236629932
## [101]  0.851566374  1.054256325  1.839758922  1.089107790  2.282569970
## [106]  0.501388394  2.310241027  1.924577740  0.701628854  1.572163933
## [111] -0.811353906  1.491858309  0.024586469  1.112575616 -0.571601276
## [116]  0.377668248 -0.188704184  2.200551532  0.137980542  0.950017590
## [121] -2.185559323  1.929037466 -0.806797583 -0.380090545 -1.144726418
## [126]  0.324724378 -0.042361431  0.262863488 -2.286748789 -1.897223008
## [131] -0.380051401  0.816209921  2.132221753  0.261903736  2.475658531
## [136]  1.600373208  1.304524934  1.819312966  1.362641279 -0.413939576
## [141]  1.261613549  0.050621698  1.056754925 -0.986731556 -1.222474981
## [146] -0.376638636  1.363648342  2.452450632  0.754805726  0.995028968
## [151]  1.576494524  0.252185400  1.371836640 -0.192063167  1.124324950
## [156]  1.373842963  0.161530570 -0.548495611  0.122079347 -0.162928307
## [161]  0.869627949  1.645302830 -0.133512418  0.577205198  1.332200135
## [166]  2.314074616  2.541704734  2.329764342  0.760551363  1.260166357
## [171] -0.545679568 -0.526906104  0.141787476 -0.865162719  0.776325959
## [176] -0.800867390 -0.892046480 -0.198269829  0.391609515 -0.323115699
## [181]  1.411984335  1.539053907  1.726604278  2.101460674  0.952816063
## [186]  0.630389142 -0.434972955  0.284244921 -0.629639814 -0.326646935
## [191]  0.071838968  0.089770764  2.391026520  0.344158345  0.726821474
## [196] -0.426357782  0.673665279  0.476988095  1.031459004 -0.824513344
## [201] -0.296015791 -1.270447231  0.741566980 -1.917525859  2.152745644
## [206] -0.934229115  0.986361102 -2.327510614 -0.836100979 -2.203163018
## [211]  1.251274713 -0.483100429  0.405541344 -1.046801129 -0.118265714
## [216] -1.479388762 -0.972990734 -1.654317862 -0.369158859  1.188879940
## [221]  0.758165612  0.004675097 -0.842823443  0.789932300 -0.806046838
## [226]  0.823141063 -1.638547001 -0.956585019 -3.511118437  0.160155860
## [231] -0.352221471  2.080835571  1.155445559  0.007319216 -0.349601438
## [236] -1.389952187 -0.480352506 -0.374425649  1.536508308  2.946040765
## [241]  2.058586017  1.043034785 -0.514395852  0.448597128 -0.107166162
## [246] -0.901895755 -0.643922756 -1.073635485 -1.848150055 -0.975969799
## [251] -1.018716345 -0.046728256 -0.457365043  0.290596707 -0.817736130
## [256] -0.285379062 -1.197053507 -0.809829780 -0.284903059  1.427407937
## [261]  2.072450303  2.578961105  0.990888560  0.130744460 -1.055302300
## [266] -0.349721522  0.489784548  0.652814461  0.864882450 -1.406581322
## [271]  0.300966391  0.964790201  1.260471246  1.745385800  0.068547273
## [276]  3.790009529  0.959858473  2.336401436 -1.004590961 -1.634457108
## [281] -0.245794766 -1.413568572 -0.134170647 -0.816912736  0.107330937
## [286] -0.639551099 -0.525883926 -1.055692764 -0.158199423 -0.107872805
## [291] -0.227482501  0.463732156 -0.382036141  0.326448357  0.727266022
## [296]  1.184649221  2.168488530  1.460507679  0.906312503  0.015317578

Karakteristik MA(2)

Plot Time Series

ts.plot(ma)

Berdasarkan plot time series, terlihat bahwa data MA(2) yang dibangkitkan stasioner dalam rataan

Plot ACF

acf(ma,lag.max = 20)

Berdasarkan plot AFC tersebut, terlihat bahwa plot ACF cuts off di lag kedua

Plot PACF

pacf(ma)

Berdasarkan plot PACF tersebut, terlihat bahwa plot PACF cenderung tails off dan membentuk gelombang sinus

Plot EACF

TSA::eacf(ma)
## AR/MA
##   0 1 2 3 4 5 6 7 8 9 10 11 12 13
## 0 x x o o o o o o o o o  o  o  o 
## 1 x x o o o o o o o o o  o  o  o 
## 2 x x o x o o o o o o o  o  o  o 
## 3 o x x x o o o o o o o  o  o  o 
## 4 x x o x o o o o o o o  o  o  o 
## 5 x x x x o x o o o o o  o  o  o 
## 6 x x x x o o o o o o o  o  o  o 
## 7 x x x x o o o o o o o  o  o  o

Berdasarkan pola segitiga nol pada plot EACF, terlihat bahwa segitiga nol berada pada ordo AR(0) dan ordo MA(2)

Scatterplot Antar Lag

Korelasi antara \(Y_t\) dengan \(Y_{t-1}\)

#Yt
yt_ma <- ma[-1]
yt_ma
##   [1]  0.132881183  0.658183657  0.021134760  3.299420916  0.915231810
##   [6]  2.256101722 -0.633709544  1.212692091  0.488247563  1.365917354
##  [11]  0.859402939 -0.283312528 -0.541257282 -2.570059470 -2.842772162
##  [16] -0.992370374 -1.067240744  2.218516529  2.200945279  2.456432824
##  [21]  2.234504393  1.795219724  2.251167470  0.790990469  1.215940621
##  [26]  0.526099293  1.094760371  1.080962605  0.908300966  1.652803499
##  [31]  1.790913751  2.372726341  0.977329459 -0.011604417  2.056545611
##  [36]  0.680957663  0.901810835  1.465150702 -0.401660786  0.319160465
##  [41] -0.522727520 -1.385340145 -1.252614832  0.060156387  0.716966475
##  [46]  0.894508358  1.499279489  0.469600491  1.402106532  0.485686038
##  [51]  1.584133220 -0.450447425 -1.134048977 -0.870574767 -1.499551006
##  [56]  1.219248831 -1.084224277  0.025365132 -1.345499887  1.256230369
##  [61]  0.885180465  0.928511990 -0.615893983 -0.629149599  2.333284252
##  [66]  1.260046662  0.928009646  0.300440456 -1.609279361 -2.243711296
##  [71] -1.228093288 -0.384008230  2.222052781  1.366946810  0.286202500
##  [76] -0.437222316  0.251184461  0.177087208  0.875363006  0.451368246
##  [81] -0.956924380 -1.007689595 -2.619731719 -0.971496099  0.016829578
##  [86]  0.261893053  0.721130841  0.072592286  0.729277777  0.252451354
##  [91]  0.368767403  0.675968503  0.852165073  0.012702662  1.669574565
##  [96]  1.868642026  0.915469178  0.359566884 -2.382471996 -1.268563372
## [101] -2.236629932  0.851566374  1.054256325  1.839758922  1.089107790
## [106]  2.282569970  0.501388394  2.310241027  1.924577740  0.701628854
## [111]  1.572163933 -0.811353906  1.491858309  0.024586469  1.112575616
## [116] -0.571601276  0.377668248 -0.188704184  2.200551532  0.137980542
## [121]  0.950017590 -2.185559323  1.929037466 -0.806797583 -0.380090545
## [126] -1.144726418  0.324724378 -0.042361431  0.262863488 -2.286748789
## [131] -1.897223008 -0.380051401  0.816209921  2.132221753  0.261903736
## [136]  2.475658531  1.600373208  1.304524934  1.819312966  1.362641279
## [141] -0.413939576  1.261613549  0.050621698  1.056754925 -0.986731556
## [146] -1.222474981 -0.376638636  1.363648342  2.452450632  0.754805726
## [151]  0.995028968  1.576494524  0.252185400  1.371836640 -0.192063167
## [156]  1.124324950  1.373842963  0.161530570 -0.548495611  0.122079347
## [161] -0.162928307  0.869627949  1.645302830 -0.133512418  0.577205198
## [166]  1.332200135  2.314074616  2.541704734  2.329764342  0.760551363
## [171]  1.260166357 -0.545679568 -0.526906104  0.141787476 -0.865162719
## [176]  0.776325959 -0.800867390 -0.892046480 -0.198269829  0.391609515
## [181] -0.323115699  1.411984335  1.539053907  1.726604278  2.101460674
## [186]  0.952816063  0.630389142 -0.434972955  0.284244921 -0.629639814
## [191] -0.326646935  0.071838968  0.089770764  2.391026520  0.344158345
## [196]  0.726821474 -0.426357782  0.673665279  0.476988095  1.031459004
## [201] -0.824513344 -0.296015791 -1.270447231  0.741566980 -1.917525859
## [206]  2.152745644 -0.934229115  0.986361102 -2.327510614 -0.836100979
## [211] -2.203163018  1.251274713 -0.483100429  0.405541344 -1.046801129
## [216] -0.118265714 -1.479388762 -0.972990734 -1.654317862 -0.369158859
## [221]  1.188879940  0.758165612  0.004675097 -0.842823443  0.789932300
## [226] -0.806046838  0.823141063 -1.638547001 -0.956585019 -3.511118437
## [231]  0.160155860 -0.352221471  2.080835571  1.155445559  0.007319216
## [236] -0.349601438 -1.389952187 -0.480352506 -0.374425649  1.536508308
## [241]  2.946040765  2.058586017  1.043034785 -0.514395852  0.448597128
## [246] -0.107166162 -0.901895755 -0.643922756 -1.073635485 -1.848150055
## [251] -0.975969799 -1.018716345 -0.046728256 -0.457365043  0.290596707
## [256] -0.817736130 -0.285379062 -1.197053507 -0.809829780 -0.284903059
## [261]  1.427407937  2.072450303  2.578961105  0.990888560  0.130744460
## [266] -1.055302300 -0.349721522  0.489784548  0.652814461  0.864882450
## [271] -1.406581322  0.300966391  0.964790201  1.260471246  1.745385800
## [276]  0.068547273  3.790009529  0.959858473  2.336401436 -1.004590961
## [281] -1.634457108 -0.245794766 -1.413568572 -0.134170647 -0.816912736
## [286]  0.107330937 -0.639551099 -0.525883926 -1.055692764 -0.158199423
## [291] -0.107872805 -0.227482501  0.463732156 -0.382036141  0.326448357
## [296]  0.727266022  1.184649221  2.168488530  1.460507679
#Yt-1
yt_1_ma <- ma[-300]
yt_1_ma
##   [1]  1.065125327  0.132881183  0.658183657  0.021134760  3.299420916
##   [6]  0.915231810  2.256101722 -0.633709544  1.212692091  0.488247563
##  [11]  1.365917354  0.859402939 -0.283312528 -0.541257282 -2.570059470
##  [16] -2.842772162 -0.992370374 -1.067240744  2.218516529  2.200945279
##  [21]  2.456432824  2.234504393  1.795219724  2.251167470  0.790990469
##  [26]  1.215940621  0.526099293  1.094760371  1.080962605  0.908300966
##  [31]  1.652803499  1.790913751  2.372726341  0.977329459 -0.011604417
##  [36]  2.056545611  0.680957663  0.901810835  1.465150702 -0.401660786
##  [41]  0.319160465 -0.522727520 -1.385340145 -1.252614832  0.060156387
##  [46]  0.716966475  0.894508358  1.499279489  0.469600491  1.402106532
##  [51]  0.485686038  1.584133220 -0.450447425 -1.134048977 -0.870574767
##  [56] -1.499551006  1.219248831 -1.084224277  0.025365132 -1.345499887
##  [61]  1.256230369  0.885180465  0.928511990 -0.615893983 -0.629149599
##  [66]  2.333284252  1.260046662  0.928009646  0.300440456 -1.609279361
##  [71] -2.243711296 -1.228093288 -0.384008230  2.222052781  1.366946810
##  [76]  0.286202500 -0.437222316  0.251184461  0.177087208  0.875363006
##  [81]  0.451368246 -0.956924380 -1.007689595 -2.619731719 -0.971496099
##  [86]  0.016829578  0.261893053  0.721130841  0.072592286  0.729277777
##  [91]  0.252451354  0.368767403  0.675968503  0.852165073  0.012702662
##  [96]  1.669574565  1.868642026  0.915469178  0.359566884 -2.382471996
## [101] -1.268563372 -2.236629932  0.851566374  1.054256325  1.839758922
## [106]  1.089107790  2.282569970  0.501388394  2.310241027  1.924577740
## [111]  0.701628854  1.572163933 -0.811353906  1.491858309  0.024586469
## [116]  1.112575616 -0.571601276  0.377668248 -0.188704184  2.200551532
## [121]  0.137980542  0.950017590 -2.185559323  1.929037466 -0.806797583
## [126] -0.380090545 -1.144726418  0.324724378 -0.042361431  0.262863488
## [131] -2.286748789 -1.897223008 -0.380051401  0.816209921  2.132221753
## [136]  0.261903736  2.475658531  1.600373208  1.304524934  1.819312966
## [141]  1.362641279 -0.413939576  1.261613549  0.050621698  1.056754925
## [146] -0.986731556 -1.222474981 -0.376638636  1.363648342  2.452450632
## [151]  0.754805726  0.995028968  1.576494524  0.252185400  1.371836640
## [156] -0.192063167  1.124324950  1.373842963  0.161530570 -0.548495611
## [161]  0.122079347 -0.162928307  0.869627949  1.645302830 -0.133512418
## [166]  0.577205198  1.332200135  2.314074616  2.541704734  2.329764342
## [171]  0.760551363  1.260166357 -0.545679568 -0.526906104  0.141787476
## [176] -0.865162719  0.776325959 -0.800867390 -0.892046480 -0.198269829
## [181]  0.391609515 -0.323115699  1.411984335  1.539053907  1.726604278
## [186]  2.101460674  0.952816063  0.630389142 -0.434972955  0.284244921
## [191] -0.629639814 -0.326646935  0.071838968  0.089770764  2.391026520
## [196]  0.344158345  0.726821474 -0.426357782  0.673665279  0.476988095
## [201]  1.031459004 -0.824513344 -0.296015791 -1.270447231  0.741566980
## [206] -1.917525859  2.152745644 -0.934229115  0.986361102 -2.327510614
## [211] -0.836100979 -2.203163018  1.251274713 -0.483100429  0.405541344
## [216] -1.046801129 -0.118265714 -1.479388762 -0.972990734 -1.654317862
## [221] -0.369158859  1.188879940  0.758165612  0.004675097 -0.842823443
## [226]  0.789932300 -0.806046838  0.823141063 -1.638547001 -0.956585019
## [231] -3.511118437  0.160155860 -0.352221471  2.080835571  1.155445559
## [236]  0.007319216 -0.349601438 -1.389952187 -0.480352506 -0.374425649
## [241]  1.536508308  2.946040765  2.058586017  1.043034785 -0.514395852
## [246]  0.448597128 -0.107166162 -0.901895755 -0.643922756 -1.073635485
## [251] -1.848150055 -0.975969799 -1.018716345 -0.046728256 -0.457365043
## [256]  0.290596707 -0.817736130 -0.285379062 -1.197053507 -0.809829780
## [261] -0.284903059  1.427407937  2.072450303  2.578961105  0.990888560
## [266]  0.130744460 -1.055302300 -0.349721522  0.489784548  0.652814461
## [271]  0.864882450 -1.406581322  0.300966391  0.964790201  1.260471246
## [276]  1.745385800  0.068547273  3.790009529  0.959858473  2.336401436
## [281] -1.004590961 -1.634457108 -0.245794766 -1.413568572 -0.134170647
## [286] -0.816912736  0.107330937 -0.639551099 -0.525883926 -1.055692764
## [291] -0.158199423 -0.107872805 -0.227482501  0.463732156 -0.382036141
## [296]  0.326448357  0.727266022  1.184649221  2.168488530
plot(y=yt_ma,x=yt_1_ma)

Berdasarkan scatterplot tersebut, terlihat bahwa terdapat hubungan positif antara \(Y_t\) dengan \(Y_{t-1}\). Hal ini sesuai dengan teori yang ada

cor(yt_ma,yt_1_ma)
## [1] 0.3786993

Korelasi antara \(Y_t\) dengan \(Y_{t-1}\) dari hasil simulasi mendekati perhitungan teoritis yaitu

\[ \rho_1=\frac{\theta_1+\theta_1\theta_2}{1+(\theta_1)^2+(\theta_2)^2}=\frac{(0.4)+(0.4*0.6)}{1+(0.4)^2+(0.6)^2}=0.42 \]

Korelasi antara \(Y_t\) dengan \(Y_{t-2}\)

#Yt
yt_ma2 <- ma[-c(1,2)]
yt_ma2
##   [1]  0.658183657  0.021134760  3.299420916  0.915231810  2.256101722
##   [6] -0.633709544  1.212692091  0.488247563  1.365917354  0.859402939
##  [11] -0.283312528 -0.541257282 -2.570059470 -2.842772162 -0.992370374
##  [16] -1.067240744  2.218516529  2.200945279  2.456432824  2.234504393
##  [21]  1.795219724  2.251167470  0.790990469  1.215940621  0.526099293
##  [26]  1.094760371  1.080962605  0.908300966  1.652803499  1.790913751
##  [31]  2.372726341  0.977329459 -0.011604417  2.056545611  0.680957663
##  [36]  0.901810835  1.465150702 -0.401660786  0.319160465 -0.522727520
##  [41] -1.385340145 -1.252614832  0.060156387  0.716966475  0.894508358
##  [46]  1.499279489  0.469600491  1.402106532  0.485686038  1.584133220
##  [51] -0.450447425 -1.134048977 -0.870574767 -1.499551006  1.219248831
##  [56] -1.084224277  0.025365132 -1.345499887  1.256230369  0.885180465
##  [61]  0.928511990 -0.615893983 -0.629149599  2.333284252  1.260046662
##  [66]  0.928009646  0.300440456 -1.609279361 -2.243711296 -1.228093288
##  [71] -0.384008230  2.222052781  1.366946810  0.286202500 -0.437222316
##  [76]  0.251184461  0.177087208  0.875363006  0.451368246 -0.956924380
##  [81] -1.007689595 -2.619731719 -0.971496099  0.016829578  0.261893053
##  [86]  0.721130841  0.072592286  0.729277777  0.252451354  0.368767403
##  [91]  0.675968503  0.852165073  0.012702662  1.669574565  1.868642026
##  [96]  0.915469178  0.359566884 -2.382471996 -1.268563372 -2.236629932
## [101]  0.851566374  1.054256325  1.839758922  1.089107790  2.282569970
## [106]  0.501388394  2.310241027  1.924577740  0.701628854  1.572163933
## [111] -0.811353906  1.491858309  0.024586469  1.112575616 -0.571601276
## [116]  0.377668248 -0.188704184  2.200551532  0.137980542  0.950017590
## [121] -2.185559323  1.929037466 -0.806797583 -0.380090545 -1.144726418
## [126]  0.324724378 -0.042361431  0.262863488 -2.286748789 -1.897223008
## [131] -0.380051401  0.816209921  2.132221753  0.261903736  2.475658531
## [136]  1.600373208  1.304524934  1.819312966  1.362641279 -0.413939576
## [141]  1.261613549  0.050621698  1.056754925 -0.986731556 -1.222474981
## [146] -0.376638636  1.363648342  2.452450632  0.754805726  0.995028968
## [151]  1.576494524  0.252185400  1.371836640 -0.192063167  1.124324950
## [156]  1.373842963  0.161530570 -0.548495611  0.122079347 -0.162928307
## [161]  0.869627949  1.645302830 -0.133512418  0.577205198  1.332200135
## [166]  2.314074616  2.541704734  2.329764342  0.760551363  1.260166357
## [171] -0.545679568 -0.526906104  0.141787476 -0.865162719  0.776325959
## [176] -0.800867390 -0.892046480 -0.198269829  0.391609515 -0.323115699
## [181]  1.411984335  1.539053907  1.726604278  2.101460674  0.952816063
## [186]  0.630389142 -0.434972955  0.284244921 -0.629639814 -0.326646935
## [191]  0.071838968  0.089770764  2.391026520  0.344158345  0.726821474
## [196] -0.426357782  0.673665279  0.476988095  1.031459004 -0.824513344
## [201] -0.296015791 -1.270447231  0.741566980 -1.917525859  2.152745644
## [206] -0.934229115  0.986361102 -2.327510614 -0.836100979 -2.203163018
## [211]  1.251274713 -0.483100429  0.405541344 -1.046801129 -0.118265714
## [216] -1.479388762 -0.972990734 -1.654317862 -0.369158859  1.188879940
## [221]  0.758165612  0.004675097 -0.842823443  0.789932300 -0.806046838
## [226]  0.823141063 -1.638547001 -0.956585019 -3.511118437  0.160155860
## [231] -0.352221471  2.080835571  1.155445559  0.007319216 -0.349601438
## [236] -1.389952187 -0.480352506 -0.374425649  1.536508308  2.946040765
## [241]  2.058586017  1.043034785 -0.514395852  0.448597128 -0.107166162
## [246] -0.901895755 -0.643922756 -1.073635485 -1.848150055 -0.975969799
## [251] -1.018716345 -0.046728256 -0.457365043  0.290596707 -0.817736130
## [256] -0.285379062 -1.197053507 -0.809829780 -0.284903059  1.427407937
## [261]  2.072450303  2.578961105  0.990888560  0.130744460 -1.055302300
## [266] -0.349721522  0.489784548  0.652814461  0.864882450 -1.406581322
## [271]  0.300966391  0.964790201  1.260471246  1.745385800  0.068547273
## [276]  3.790009529  0.959858473  2.336401436 -1.004590961 -1.634457108
## [281] -0.245794766 -1.413568572 -0.134170647 -0.816912736  0.107330937
## [286] -0.639551099 -0.525883926 -1.055692764 -0.158199423 -0.107872805
## [291] -0.227482501  0.463732156 -0.382036141  0.326448357  0.727266022
## [296]  1.184649221  2.168488530  1.460507679
#Yt-2
yt_2_ma <- ma[-c(299,300)]
yt_2_ma
##   [1]  1.065125327  0.132881183  0.658183657  0.021134760  3.299420916
##   [6]  0.915231810  2.256101722 -0.633709544  1.212692091  0.488247563
##  [11]  1.365917354  0.859402939 -0.283312528 -0.541257282 -2.570059470
##  [16] -2.842772162 -0.992370374 -1.067240744  2.218516529  2.200945279
##  [21]  2.456432824  2.234504393  1.795219724  2.251167470  0.790990469
##  [26]  1.215940621  0.526099293  1.094760371  1.080962605  0.908300966
##  [31]  1.652803499  1.790913751  2.372726341  0.977329459 -0.011604417
##  [36]  2.056545611  0.680957663  0.901810835  1.465150702 -0.401660786
##  [41]  0.319160465 -0.522727520 -1.385340145 -1.252614832  0.060156387
##  [46]  0.716966475  0.894508358  1.499279489  0.469600491  1.402106532
##  [51]  0.485686038  1.584133220 -0.450447425 -1.134048977 -0.870574767
##  [56] -1.499551006  1.219248831 -1.084224277  0.025365132 -1.345499887
##  [61]  1.256230369  0.885180465  0.928511990 -0.615893983 -0.629149599
##  [66]  2.333284252  1.260046662  0.928009646  0.300440456 -1.609279361
##  [71] -2.243711296 -1.228093288 -0.384008230  2.222052781  1.366946810
##  [76]  0.286202500 -0.437222316  0.251184461  0.177087208  0.875363006
##  [81]  0.451368246 -0.956924380 -1.007689595 -2.619731719 -0.971496099
##  [86]  0.016829578  0.261893053  0.721130841  0.072592286  0.729277777
##  [91]  0.252451354  0.368767403  0.675968503  0.852165073  0.012702662
##  [96]  1.669574565  1.868642026  0.915469178  0.359566884 -2.382471996
## [101] -1.268563372 -2.236629932  0.851566374  1.054256325  1.839758922
## [106]  1.089107790  2.282569970  0.501388394  2.310241027  1.924577740
## [111]  0.701628854  1.572163933 -0.811353906  1.491858309  0.024586469
## [116]  1.112575616 -0.571601276  0.377668248 -0.188704184  2.200551532
## [121]  0.137980542  0.950017590 -2.185559323  1.929037466 -0.806797583
## [126] -0.380090545 -1.144726418  0.324724378 -0.042361431  0.262863488
## [131] -2.286748789 -1.897223008 -0.380051401  0.816209921  2.132221753
## [136]  0.261903736  2.475658531  1.600373208  1.304524934  1.819312966
## [141]  1.362641279 -0.413939576  1.261613549  0.050621698  1.056754925
## [146] -0.986731556 -1.222474981 -0.376638636  1.363648342  2.452450632
## [151]  0.754805726  0.995028968  1.576494524  0.252185400  1.371836640
## [156] -0.192063167  1.124324950  1.373842963  0.161530570 -0.548495611
## [161]  0.122079347 -0.162928307  0.869627949  1.645302830 -0.133512418
## [166]  0.577205198  1.332200135  2.314074616  2.541704734  2.329764342
## [171]  0.760551363  1.260166357 -0.545679568 -0.526906104  0.141787476
## [176] -0.865162719  0.776325959 -0.800867390 -0.892046480 -0.198269829
## [181]  0.391609515 -0.323115699  1.411984335  1.539053907  1.726604278
## [186]  2.101460674  0.952816063  0.630389142 -0.434972955  0.284244921
## [191] -0.629639814 -0.326646935  0.071838968  0.089770764  2.391026520
## [196]  0.344158345  0.726821474 -0.426357782  0.673665279  0.476988095
## [201]  1.031459004 -0.824513344 -0.296015791 -1.270447231  0.741566980
## [206] -1.917525859  2.152745644 -0.934229115  0.986361102 -2.327510614
## [211] -0.836100979 -2.203163018  1.251274713 -0.483100429  0.405541344
## [216] -1.046801129 -0.118265714 -1.479388762 -0.972990734 -1.654317862
## [221] -0.369158859  1.188879940  0.758165612  0.004675097 -0.842823443
## [226]  0.789932300 -0.806046838  0.823141063 -1.638547001 -0.956585019
## [231] -3.511118437  0.160155860 -0.352221471  2.080835571  1.155445559
## [236]  0.007319216 -0.349601438 -1.389952187 -0.480352506 -0.374425649
## [241]  1.536508308  2.946040765  2.058586017  1.043034785 -0.514395852
## [246]  0.448597128 -0.107166162 -0.901895755 -0.643922756 -1.073635485
## [251] -1.848150055 -0.975969799 -1.018716345 -0.046728256 -0.457365043
## [256]  0.290596707 -0.817736130 -0.285379062 -1.197053507 -0.809829780
## [261] -0.284903059  1.427407937  2.072450303  2.578961105  0.990888560
## [266]  0.130744460 -1.055302300 -0.349721522  0.489784548  0.652814461
## [271]  0.864882450 -1.406581322  0.300966391  0.964790201  1.260471246
## [276]  1.745385800  0.068547273  3.790009529  0.959858473  2.336401436
## [281] -1.004590961 -1.634457108 -0.245794766 -1.413568572 -0.134170647
## [286] -0.816912736  0.107330937 -0.639551099 -0.525883926 -1.055692764
## [291] -0.158199423 -0.107872805 -0.227482501  0.463732156 -0.382036141
## [296]  0.326448357  0.727266022  1.184649221
plot(y=yt_ma2,x=yt_2_ma)

Berdasarkan scatterplot tersebut, terlihat bahwa terdapat hubungan positif antara \(Y_t\) dengan \(Y_{t-2}\). Hal ini sesuai dengan teori yang ada

cor(yt_ma2,yt_2_ma)
## [1] 0.3897844

Korelasi antara \(Y_t\) dengan \(Y_{t-3}\)

#Yt
yt_ma3 <- ma[-c(1,2,3)]
yt_ma3
##   [1]  0.021134760  3.299420916  0.915231810  2.256101722 -0.633709544
##   [6]  1.212692091  0.488247563  1.365917354  0.859402939 -0.283312528
##  [11] -0.541257282 -2.570059470 -2.842772162 -0.992370374 -1.067240744
##  [16]  2.218516529  2.200945279  2.456432824  2.234504393  1.795219724
##  [21]  2.251167470  0.790990469  1.215940621  0.526099293  1.094760371
##  [26]  1.080962605  0.908300966  1.652803499  1.790913751  2.372726341
##  [31]  0.977329459 -0.011604417  2.056545611  0.680957663  0.901810835
##  [36]  1.465150702 -0.401660786  0.319160465 -0.522727520 -1.385340145
##  [41] -1.252614832  0.060156387  0.716966475  0.894508358  1.499279489
##  [46]  0.469600491  1.402106532  0.485686038  1.584133220 -0.450447425
##  [51] -1.134048977 -0.870574767 -1.499551006  1.219248831 -1.084224277
##  [56]  0.025365132 -1.345499887  1.256230369  0.885180465  0.928511990
##  [61] -0.615893983 -0.629149599  2.333284252  1.260046662  0.928009646
##  [66]  0.300440456 -1.609279361 -2.243711296 -1.228093288 -0.384008230
##  [71]  2.222052781  1.366946810  0.286202500 -0.437222316  0.251184461
##  [76]  0.177087208  0.875363006  0.451368246 -0.956924380 -1.007689595
##  [81] -2.619731719 -0.971496099  0.016829578  0.261893053  0.721130841
##  [86]  0.072592286  0.729277777  0.252451354  0.368767403  0.675968503
##  [91]  0.852165073  0.012702662  1.669574565  1.868642026  0.915469178
##  [96]  0.359566884 -2.382471996 -1.268563372 -2.236629932  0.851566374
## [101]  1.054256325  1.839758922  1.089107790  2.282569970  0.501388394
## [106]  2.310241027  1.924577740  0.701628854  1.572163933 -0.811353906
## [111]  1.491858309  0.024586469  1.112575616 -0.571601276  0.377668248
## [116] -0.188704184  2.200551532  0.137980542  0.950017590 -2.185559323
## [121]  1.929037466 -0.806797583 -0.380090545 -1.144726418  0.324724378
## [126] -0.042361431  0.262863488 -2.286748789 -1.897223008 -0.380051401
## [131]  0.816209921  2.132221753  0.261903736  2.475658531  1.600373208
## [136]  1.304524934  1.819312966  1.362641279 -0.413939576  1.261613549
## [141]  0.050621698  1.056754925 -0.986731556 -1.222474981 -0.376638636
## [146]  1.363648342  2.452450632  0.754805726  0.995028968  1.576494524
## [151]  0.252185400  1.371836640 -0.192063167  1.124324950  1.373842963
## [156]  0.161530570 -0.548495611  0.122079347 -0.162928307  0.869627949
## [161]  1.645302830 -0.133512418  0.577205198  1.332200135  2.314074616
## [166]  2.541704734  2.329764342  0.760551363  1.260166357 -0.545679568
## [171] -0.526906104  0.141787476 -0.865162719  0.776325959 -0.800867390
## [176] -0.892046480 -0.198269829  0.391609515 -0.323115699  1.411984335
## [181]  1.539053907  1.726604278  2.101460674  0.952816063  0.630389142
## [186] -0.434972955  0.284244921 -0.629639814 -0.326646935  0.071838968
## [191]  0.089770764  2.391026520  0.344158345  0.726821474 -0.426357782
## [196]  0.673665279  0.476988095  1.031459004 -0.824513344 -0.296015791
## [201] -1.270447231  0.741566980 -1.917525859  2.152745644 -0.934229115
## [206]  0.986361102 -2.327510614 -0.836100979 -2.203163018  1.251274713
## [211] -0.483100429  0.405541344 -1.046801129 -0.118265714 -1.479388762
## [216] -0.972990734 -1.654317862 -0.369158859  1.188879940  0.758165612
## [221]  0.004675097 -0.842823443  0.789932300 -0.806046838  0.823141063
## [226] -1.638547001 -0.956585019 -3.511118437  0.160155860 -0.352221471
## [231]  2.080835571  1.155445559  0.007319216 -0.349601438 -1.389952187
## [236] -0.480352506 -0.374425649  1.536508308  2.946040765  2.058586017
## [241]  1.043034785 -0.514395852  0.448597128 -0.107166162 -0.901895755
## [246] -0.643922756 -1.073635485 -1.848150055 -0.975969799 -1.018716345
## [251] -0.046728256 -0.457365043  0.290596707 -0.817736130 -0.285379062
## [256] -1.197053507 -0.809829780 -0.284903059  1.427407937  2.072450303
## [261]  2.578961105  0.990888560  0.130744460 -1.055302300 -0.349721522
## [266]  0.489784548  0.652814461  0.864882450 -1.406581322  0.300966391
## [271]  0.964790201  1.260471246  1.745385800  0.068547273  3.790009529
## [276]  0.959858473  2.336401436 -1.004590961 -1.634457108 -0.245794766
## [281] -1.413568572 -0.134170647 -0.816912736  0.107330937 -0.639551099
## [286] -0.525883926 -1.055692764 -0.158199423 -0.107872805 -0.227482501
## [291]  0.463732156 -0.382036141  0.326448357  0.727266022  1.184649221
## [296]  2.168488530  1.460507679
#Yt-3
yt_3_ma <- ma[-c(298,299,300)]
yt_3_ma
##   [1]  1.065125327  0.132881183  0.658183657  0.021134760  3.299420916
##   [6]  0.915231810  2.256101722 -0.633709544  1.212692091  0.488247563
##  [11]  1.365917354  0.859402939 -0.283312528 -0.541257282 -2.570059470
##  [16] -2.842772162 -0.992370374 -1.067240744  2.218516529  2.200945279
##  [21]  2.456432824  2.234504393  1.795219724  2.251167470  0.790990469
##  [26]  1.215940621  0.526099293  1.094760371  1.080962605  0.908300966
##  [31]  1.652803499  1.790913751  2.372726341  0.977329459 -0.011604417
##  [36]  2.056545611  0.680957663  0.901810835  1.465150702 -0.401660786
##  [41]  0.319160465 -0.522727520 -1.385340145 -1.252614832  0.060156387
##  [46]  0.716966475  0.894508358  1.499279489  0.469600491  1.402106532
##  [51]  0.485686038  1.584133220 -0.450447425 -1.134048977 -0.870574767
##  [56] -1.499551006  1.219248831 -1.084224277  0.025365132 -1.345499887
##  [61]  1.256230369  0.885180465  0.928511990 -0.615893983 -0.629149599
##  [66]  2.333284252  1.260046662  0.928009646  0.300440456 -1.609279361
##  [71] -2.243711296 -1.228093288 -0.384008230  2.222052781  1.366946810
##  [76]  0.286202500 -0.437222316  0.251184461  0.177087208  0.875363006
##  [81]  0.451368246 -0.956924380 -1.007689595 -2.619731719 -0.971496099
##  [86]  0.016829578  0.261893053  0.721130841  0.072592286  0.729277777
##  [91]  0.252451354  0.368767403  0.675968503  0.852165073  0.012702662
##  [96]  1.669574565  1.868642026  0.915469178  0.359566884 -2.382471996
## [101] -1.268563372 -2.236629932  0.851566374  1.054256325  1.839758922
## [106]  1.089107790  2.282569970  0.501388394  2.310241027  1.924577740
## [111]  0.701628854  1.572163933 -0.811353906  1.491858309  0.024586469
## [116]  1.112575616 -0.571601276  0.377668248 -0.188704184  2.200551532
## [121]  0.137980542  0.950017590 -2.185559323  1.929037466 -0.806797583
## [126] -0.380090545 -1.144726418  0.324724378 -0.042361431  0.262863488
## [131] -2.286748789 -1.897223008 -0.380051401  0.816209921  2.132221753
## [136]  0.261903736  2.475658531  1.600373208  1.304524934  1.819312966
## [141]  1.362641279 -0.413939576  1.261613549  0.050621698  1.056754925
## [146] -0.986731556 -1.222474981 -0.376638636  1.363648342  2.452450632
## [151]  0.754805726  0.995028968  1.576494524  0.252185400  1.371836640
## [156] -0.192063167  1.124324950  1.373842963  0.161530570 -0.548495611
## [161]  0.122079347 -0.162928307  0.869627949  1.645302830 -0.133512418
## [166]  0.577205198  1.332200135  2.314074616  2.541704734  2.329764342
## [171]  0.760551363  1.260166357 -0.545679568 -0.526906104  0.141787476
## [176] -0.865162719  0.776325959 -0.800867390 -0.892046480 -0.198269829
## [181]  0.391609515 -0.323115699  1.411984335  1.539053907  1.726604278
## [186]  2.101460674  0.952816063  0.630389142 -0.434972955  0.284244921
## [191] -0.629639814 -0.326646935  0.071838968  0.089770764  2.391026520
## [196]  0.344158345  0.726821474 -0.426357782  0.673665279  0.476988095
## [201]  1.031459004 -0.824513344 -0.296015791 -1.270447231  0.741566980
## [206] -1.917525859  2.152745644 -0.934229115  0.986361102 -2.327510614
## [211] -0.836100979 -2.203163018  1.251274713 -0.483100429  0.405541344
## [216] -1.046801129 -0.118265714 -1.479388762 -0.972990734 -1.654317862
## [221] -0.369158859  1.188879940  0.758165612  0.004675097 -0.842823443
## [226]  0.789932300 -0.806046838  0.823141063 -1.638547001 -0.956585019
## [231] -3.511118437  0.160155860 -0.352221471  2.080835571  1.155445559
## [236]  0.007319216 -0.349601438 -1.389952187 -0.480352506 -0.374425649
## [241]  1.536508308  2.946040765  2.058586017  1.043034785 -0.514395852
## [246]  0.448597128 -0.107166162 -0.901895755 -0.643922756 -1.073635485
## [251] -1.848150055 -0.975969799 -1.018716345 -0.046728256 -0.457365043
## [256]  0.290596707 -0.817736130 -0.285379062 -1.197053507 -0.809829780
## [261] -0.284903059  1.427407937  2.072450303  2.578961105  0.990888560
## [266]  0.130744460 -1.055302300 -0.349721522  0.489784548  0.652814461
## [271]  0.864882450 -1.406581322  0.300966391  0.964790201  1.260471246
## [276]  1.745385800  0.068547273  3.790009529  0.959858473  2.336401436
## [281] -1.004590961 -1.634457108 -0.245794766 -1.413568572 -0.134170647
## [286] -0.816912736  0.107330937 -0.639551099 -0.525883926 -1.055692764
## [291] -0.158199423 -0.107872805 -0.227482501  0.463732156 -0.382036141
## [296]  0.326448357  0.727266022
plot(y=yt_ma3,x=yt_3_ma)

Berdasarkan scatterplot tersebut, terlihat bahwa cenderung tidak terdapat hubungan antara \(Y_t\) dengan \(Y_{t-3}\).

cor(yt_ma3,yt_3_ma)
## [1] -0.07842954

Korelasi antara \(Y_t\) dengan \(Y_{t-3}\) hasil simulasi mendekati teori yang ada yaitu 0.

Proses AR

Proses AR dapat dituliskan sebagai berikut:

\[ y_{t} = c + e_t + \phi_{1}Y_{t-1} + \phi_{2}Y_{t-2} + \dots + \phi_{q}Y_{t-q} = c+{e_t+\sum_{i=1}^p \phi_iY_{t-i}} \] Terlihat bahwa \(Y_t\) berperan penting dalam pembangkitan proses AR.

Pembangkitan Proses AR

Akan dicoba membangkitkan proses AR, yaitu AR(2) dengan \(\phi1 = 0.5\) dan \(\phi2 =0.2\) sebanyak 300 observasi dan \(c=0\).

set.seed(035)

Nilai-nilai selanjutnya dapat dicari melalui loop. Bentuk loop dapat dilihat dari rumus AR(2) yang hendak dibangkitkan:

\[ Y_t = e_t+0.5Y_{t-1}+0.2Y_{t-2} \]

n<-length(wn)
n
## [1] 300
ar <- c(1:n) #bangkitkan data ar 1-300
for (i in 3:n) {ar[i]<-wn[i]+0.5*ar[i-1]+0.2*ar[i-2]} #looping dari 3-300
ar
##   [1]  1.000000000  2.000000000  1.165955987  0.938001648  4.040029883
##   [6]  1.814697744  2.125920865  0.863714547  2.048268102  1.545945122
##  [11]  1.694180277  1.601619567  0.371264692  0.004847193 -1.831910620
##  [16] -2.693657731 -0.848960327 -1.308949603  1.013994421  1.918290789
##  [21]  1.846186931  2.263708856  2.502983054  2.980469932  1.670192649
##  [26]  2.009644523  1.825961756  1.867757240  1.866634014  1.656435730
##  [31]  2.373983431  2.630476742  3.014418988  1.853562001  0.855327159
##  [36]  3.232502351  1.899226305  0.992684756  2.515564069  0.760964948
##  [41]  0.497271510  0.449843159 -0.848775762 -1.147182073  0.345806314
##  [46]  0.712429910  0.358807807  1.386418838  0.848700937  1.431531414
##  [51]  1.028995087  1.889603063  0.178539914 -0.931313695 -0.157885545
##  [56] -1.034479287  0.814903596 -0.967592210 -0.646423203 -1.031097913
##  [61]  1.012508610  0.830899026  0.339712179 -0.487081048 -0.308557477
##  [66]  2.628643225  1.440297143  0.370609149  1.011299471 -0.719521142
##  [71] -2.204256171 -0.875847780 -0.182803871  1.454982068  0.951672894
##  [76] -0.084193829 -0.105019556  0.793754820  0.359673693  0.702568720
##  [81]  0.738714864 -0.791640056 -0.924459617 -2.188829775 -1.217664591
##  [86] -0.113462388 -0.448610736 -0.026409873 -0.029562012  0.547515984
##  [91]  0.249246315  0.269786088  0.857606481  1.044384022  0.078048040
##  [96]  1.826767358  2.535487860  0.958648831  0.651871556 -1.326317137
## [101] -0.863024298 -1.694919884  0.428903320  0.949023345  1.101248120
## [106]  0.969020809  2.571319697  1.097073289  2.406062099  3.039153274
## [111]  1.249777975  2.135263468  0.595822542  1.964001893  1.063195625
## [116]  1.308738982  0.164452921  0.772060309  0.480515551  2.313731813
## [121]  0.586367881  0.821151162 -1.283837828  2.136891063  0.046060676
## [126] -1.192182925 -0.615198781  0.775571069 -0.289266798 -0.298014894
## [131] -2.037803766 -2.058253261 -0.326273649  0.385105991  1.209314391
## [136] -0.065160402  2.334467051  2.352604180  1.193248716  2.347395232
## [141]  2.532856694  0.105614061  1.800803650  1.453752222  1.186045563
## [146] -0.461898370 -0.737351648  0.267153454  1.504638104  2.213862321
## [151]  0.688300452  1.224907443  2.583149433  0.792736505  1.482541286
## [156]  0.926229339  1.531657431  2.000256908  0.585096878 -0.196859960
## [161]  0.929270492  0.431738377  0.722352528  1.960689999  0.193659119
## [166]  0.530735676  2.178286382  2.734629384  2.604429048  2.934718476
## [171]  1.833690933  2.174430319  0.732749784  0.160451582  1.057609111
## [176] -0.252115568  0.688494155 -0.260449209 -1.024681055 -0.017274182
## [181]  0.578466907 -0.682446878  1.098520350  2.003139840  1.517300407
## [186]  2.188106855  1.761182249  1.185836932  0.344930942  1.013392706
## [191]  0.064673172 -0.249483969  0.460436878  0.331894176  2.245085434
## [196]  0.647315990  0.523908198  0.389529606  1.123226928  0.788167901
## [201]  1.096520643 -0.398925074 -0.120921393 -0.691496363  0.676592571
## [206] -1.805388468  1.559609098 -0.243064899  0.045276283 -1.898365165
## [211] -0.940204322 -1.929473218  0.530422647 -0.629244983 -0.609492025
## [216] -1.011877515 -0.273017437 -1.611431370 -1.537182882 -1.710921804
## [221] -0.877920476  0.665770994  0.165714575 -0.650828041 -0.793406642
## [226]  0.983621301 -0.776432286  0.169179685 -1.187775278 -1.286208196
## [231] -3.431067795 -0.356762324 -0.332976293  0.660739661  0.740816965
## [236] -0.220089489 -0.308649864 -1.016000070 -0.514958510 -0.366419173
## [241]  1.179740082  2.819694366  1.903573130  1.073784155  0.425320607
## [246]  1.338093471  0.578045818 -0.821233938 -0.282141322 -0.557374202
## [251] -2.090162609 -1.279272994 -0.974270278 -0.749447380 -1.074398976
## [256] -0.190689179 -1.023627691 -0.847809291 -1.278498663 -1.179979012
## [261] -0.592204081  1.016616724  1.690740927  2.178076820  1.185797922
## [266]  0.578184447 -0.204085336  0.226205484  0.915228004  0.690925870
## [271]  0.812397280 -1.088595469  0.402006579  1.614332024  1.025324528
## [276]  1.547182892  0.679887615  4.131904876  1.948039880  2.148843690
## [281]  0.472395798 -0.780902527  0.631961209 -0.756820300 -0.576300383
## [286] -0.576741758 -0.046839531 -0.838699282 -0.888703862 -1.063831326
## [291] -0.411168254 -0.374574747 -0.693606692  0.185382740 -0.416455123
## [296] -0.060793215  0.791690363  1.139969883  2.051071409  1.731167996

Selain menggunakan cara di atas, pembangkitan proses AR dapat dilakukan dengan fungsi arima.sim() sebagai berikut.

ar2 <- arima.sim(list(order=c(2,0,0), ar=c(0.5,0.2)), n=300)
ar2
## Time Series:
## Start = 1 
## End = 300 
## Frequency = 1 
##   [1]  2.00818916  1.82485226  1.86691142  1.86598921  1.65594416  2.37360869
##   [7]  2.63019106  3.01420120  1.85339597  0.85520058  3.23240586  1.89915274
##  [13]  0.99262868  2.51552132  0.76093236  0.49724666  0.44982422 -0.84879020
##  [19] -1.14719308  0.34579792  0.71242351  0.35880293  1.38641512  0.84869810
##  [25]  1.43152925  1.02899344  1.88960181  0.17853896 -0.93131443 -0.15788610
##  [31] -1.03447971  0.81490327 -0.96759246 -0.64642339 -1.03109806  1.01250850
##  [37]  0.83089894  0.33971212 -0.48708110 -0.30855751  2.62864320  1.44029712
##  [43]  0.37060913  1.01129946 -0.71952115 -2.20425618 -0.87584779 -0.18280388
##  [49]  1.45498206  0.95167289 -0.08419383 -0.10501956  0.79375482  0.35967369
##  [55]  0.70256872  0.73871486 -0.79164006 -0.92445962 -2.18882978 -1.21766459
##  [61] -0.11346239 -0.44861074 -0.02640987 -0.02956201  0.54751598  0.24924632
##  [67]  0.26978609  0.85760648  1.04438402  0.07804804  1.82676736  2.53548786
##  [73]  0.95864883  0.65187156 -1.32631714 -0.86302430 -1.69491988  0.42890332
##  [79]  0.94902334  1.10124812  0.96902081  2.57131970  1.09707329  2.40606210
##  [85]  3.03915327  1.24977797  2.13526347  0.59582254  1.96400189  1.06319563
##  [91]  1.30873898  0.16445292  0.77206031  0.48051555  2.31373181  0.58636788
##  [97]  0.82115116 -1.28383783  2.13689106  0.04606068 -1.19218293 -0.61519878
## [103]  0.77557107 -0.28926680 -0.29801489 -2.03780377 -2.05825326 -0.32627365
## [109]  0.38510599  1.20931439 -0.06516040  2.33446705  2.35260418  1.19324872
## [115]  2.34739523  2.53285669  0.10561406  1.80080365  1.45375222  1.18604556
## [121] -0.46189837 -0.73735165  0.26715345  1.50463810  2.21386232  0.68830045
## [127]  1.22490744  2.58314943  0.79273651  1.48254129  0.92622934  1.53165743
## [133]  2.00025691  0.58509688 -0.19685996  0.92927049  0.43173838  0.72235253
## [139]  1.96069000  0.19365912  0.53073568  2.17828638  2.73462938  2.60442905
## [145]  2.93471848  1.83369093  2.17443032  0.73274978  0.16045158  1.05760911
## [151] -0.25211557  0.68849415 -0.26044921 -1.02468105 -0.01727418  0.57846691
## [157] -0.68244688  1.09852035  2.00313984  1.51730041  2.18810685  1.76118225
## [163]  1.18583693  0.34493094  1.01339271  0.06467317 -0.24948397  0.46043688
## [169]  0.33189418  2.24508543  0.64731599  0.52390820  0.38952961  1.12322693
## [175]  0.78816790  1.09652064 -0.39892507 -0.12092139 -0.69149636  0.67659257
## [181] -1.80538847  1.55960910 -0.24306490  0.04527628 -1.89836517 -0.94020432
## [187] -1.92947322  0.53042265 -0.62924498 -0.60949203 -1.01187752 -0.27301744
## [193] -1.61143137 -1.53718288 -1.71092180 -0.87792048  0.66577099  0.16571458
## [199] -0.65082804 -0.79340664  0.98362130 -0.77643229  0.16917969 -1.18777528
## [205] -1.28620820 -3.43106780 -0.35676232 -0.33297629  0.66073966  0.74081696
## [211] -0.22008949 -0.30864986 -1.01600007 -0.51495851 -0.36641917  1.17974008
## [217]  2.81969437  1.90357313  1.07378416  0.42532061  1.33809347  0.57804582
## [223] -0.82123394 -0.28214132 -0.55737420 -2.09016261 -1.27927299 -0.97427028
## [229] -0.74944738 -1.07439898 -0.19068918 -1.02362769 -0.84780929 -1.27849866
## [235] -1.17997901 -0.59220408  1.01661672  1.69074093  2.17807682  1.18579792
## [241]  0.57818445 -0.20408534  0.22620548  0.91522800  0.69092587  0.81239728
## [247] -1.08859547  0.40200658  1.61433202  1.02532453  1.54718289  0.67988762
## [253]  4.13190488  1.94803988  2.14884369  0.47239580 -0.78090253  0.63196121
## [259] -0.75682030 -0.57630038 -0.57674176 -0.04683953 -0.83869928 -0.88870386
## [265] -1.06383133 -0.41116825 -0.37457475 -0.69360669  0.18538274 -0.41645512
## [271] -0.06079322  0.79169036  1.13996988  2.05107141  1.73116800  1.19740642
## [277]  0.70502814 -0.22680948 -1.79624497  0.32076174  0.11096382 -0.60337812
## [283]  0.62364119  0.62389796 -0.86150603 -1.47019425  0.93723550  0.11466766
## [289] -0.60234407 -0.36651407  1.54541404  0.03869346  2.11701028  2.27701311
## [295]  1.92245855  3.11631323  3.05576558  0.96483684  1.16321356 -0.05515815

Karakteristik AR(2)

Plot Time Series

ts.plot(ar)

Berdasarkan plot time series tersebut terlihat bahwa data cenderung stasioner pada rataan

Plot ACF

acf(ar)

Berdasarkan plot ACF tersebut terlihat bahwa plot ACF cenderung tails off dan cenderung membentuk pola grafik sinus

Plot PACF

pacf(ar)

Berdasarkan plot PACF tersebut, terlihat bahwa plot PACF cuts off pada lag kedua, sejalan dengan teori yang ada

Plot EACF

TSA::eacf(ar)
## AR/MA
##   0 1 2 3 4 5 6 7 8 9 10 11 12 13
## 0 x x x x x o o o o o o  o  o  o 
## 1 x x o o o o o o o o o  o  o  o 
## 2 x o o o o o o o o o o  o  o  o 
## 3 x o o o o o o o o o o  o  o  o 
## 4 x x o o o o o o o o o  o  o  o 
## 5 x x o o o o o o o o o  o  o  o 
## 6 x x o x x o o o o o o  o  o  o 
## 7 x x o o x o o o o o o  o  o  o

Berdasarkan pola segitiga nol pada plot EACF, terlihat bahwa segitiga nol berada pada ordo AR(2) dan ordo MA(1)

Scatterplot Antar Lag

Korelasi antara \(Y_t\) dengan \(Y_{t-1}\)

#Yt
yt_ar <- ar[-1]
yt_ar
##   [1]  2.000000000  1.165955987  0.938001648  4.040029883  1.814697744
##   [6]  2.125920865  0.863714547  2.048268102  1.545945122  1.694180277
##  [11]  1.601619567  0.371264692  0.004847193 -1.831910620 -2.693657731
##  [16] -0.848960327 -1.308949603  1.013994421  1.918290789  1.846186931
##  [21]  2.263708856  2.502983054  2.980469932  1.670192649  2.009644523
##  [26]  1.825961756  1.867757240  1.866634014  1.656435730  2.373983431
##  [31]  2.630476742  3.014418988  1.853562001  0.855327159  3.232502351
##  [36]  1.899226305  0.992684756  2.515564069  0.760964948  0.497271510
##  [41]  0.449843159 -0.848775762 -1.147182073  0.345806314  0.712429910
##  [46]  0.358807807  1.386418838  0.848700937  1.431531414  1.028995087
##  [51]  1.889603063  0.178539914 -0.931313695 -0.157885545 -1.034479287
##  [56]  0.814903596 -0.967592210 -0.646423203 -1.031097913  1.012508610
##  [61]  0.830899026  0.339712179 -0.487081048 -0.308557477  2.628643225
##  [66]  1.440297143  0.370609149  1.011299471 -0.719521142 -2.204256171
##  [71] -0.875847780 -0.182803871  1.454982068  0.951672894 -0.084193829
##  [76] -0.105019556  0.793754820  0.359673693  0.702568720  0.738714864
##  [81] -0.791640056 -0.924459617 -2.188829775 -1.217664591 -0.113462388
##  [86] -0.448610736 -0.026409873 -0.029562012  0.547515984  0.249246315
##  [91]  0.269786088  0.857606481  1.044384022  0.078048040  1.826767358
##  [96]  2.535487860  0.958648831  0.651871556 -1.326317137 -0.863024298
## [101] -1.694919884  0.428903320  0.949023345  1.101248120  0.969020809
## [106]  2.571319697  1.097073289  2.406062099  3.039153274  1.249777975
## [111]  2.135263468  0.595822542  1.964001893  1.063195625  1.308738982
## [116]  0.164452921  0.772060309  0.480515551  2.313731813  0.586367881
## [121]  0.821151162 -1.283837828  2.136891063  0.046060676 -1.192182925
## [126] -0.615198781  0.775571069 -0.289266798 -0.298014894 -2.037803766
## [131] -2.058253261 -0.326273649  0.385105991  1.209314391 -0.065160402
## [136]  2.334467051  2.352604180  1.193248716  2.347395232  2.532856694
## [141]  0.105614061  1.800803650  1.453752222  1.186045563 -0.461898370
## [146] -0.737351648  0.267153454  1.504638104  2.213862321  0.688300452
## [151]  1.224907443  2.583149433  0.792736505  1.482541286  0.926229339
## [156]  1.531657431  2.000256908  0.585096878 -0.196859960  0.929270492
## [161]  0.431738377  0.722352528  1.960689999  0.193659119  0.530735676
## [166]  2.178286382  2.734629384  2.604429048  2.934718476  1.833690933
## [171]  2.174430319  0.732749784  0.160451582  1.057609111 -0.252115568
## [176]  0.688494155 -0.260449209 -1.024681055 -0.017274182  0.578466907
## [181] -0.682446878  1.098520350  2.003139840  1.517300407  2.188106855
## [186]  1.761182249  1.185836932  0.344930942  1.013392706  0.064673172
## [191] -0.249483969  0.460436878  0.331894176  2.245085434  0.647315990
## [196]  0.523908198  0.389529606  1.123226928  0.788167901  1.096520643
## [201] -0.398925074 -0.120921393 -0.691496363  0.676592571 -1.805388468
## [206]  1.559609098 -0.243064899  0.045276283 -1.898365165 -0.940204322
## [211] -1.929473218  0.530422647 -0.629244983 -0.609492025 -1.011877515
## [216] -0.273017437 -1.611431370 -1.537182882 -1.710921804 -0.877920476
## [221]  0.665770994  0.165714575 -0.650828041 -0.793406642  0.983621301
## [226] -0.776432286  0.169179685 -1.187775278 -1.286208196 -3.431067795
## [231] -0.356762324 -0.332976293  0.660739661  0.740816965 -0.220089489
## [236] -0.308649864 -1.016000070 -0.514958510 -0.366419173  1.179740082
## [241]  2.819694366  1.903573130  1.073784155  0.425320607  1.338093471
## [246]  0.578045818 -0.821233938 -0.282141322 -0.557374202 -2.090162609
## [251] -1.279272994 -0.974270278 -0.749447380 -1.074398976 -0.190689179
## [256] -1.023627691 -0.847809291 -1.278498663 -1.179979012 -0.592204081
## [261]  1.016616724  1.690740927  2.178076820  1.185797922  0.578184447
## [266] -0.204085336  0.226205484  0.915228004  0.690925870  0.812397280
## [271] -1.088595469  0.402006579  1.614332024  1.025324528  1.547182892
## [276]  0.679887615  4.131904876  1.948039880  2.148843690  0.472395798
## [281] -0.780902527  0.631961209 -0.756820300 -0.576300383 -0.576741758
## [286] -0.046839531 -0.838699282 -0.888703862 -1.063831326 -0.411168254
## [291] -0.374574747 -0.693606692  0.185382740 -0.416455123 -0.060793215
## [296]  0.791690363  1.139969883  2.051071409  1.731167996
#Yt-1
yt_1_ar <- ar[-300]
yt_1_ar
##   [1]  1.000000000  2.000000000  1.165955987  0.938001648  4.040029883
##   [6]  1.814697744  2.125920865  0.863714547  2.048268102  1.545945122
##  [11]  1.694180277  1.601619567  0.371264692  0.004847193 -1.831910620
##  [16] -2.693657731 -0.848960327 -1.308949603  1.013994421  1.918290789
##  [21]  1.846186931  2.263708856  2.502983054  2.980469932  1.670192649
##  [26]  2.009644523  1.825961756  1.867757240  1.866634014  1.656435730
##  [31]  2.373983431  2.630476742  3.014418988  1.853562001  0.855327159
##  [36]  3.232502351  1.899226305  0.992684756  2.515564069  0.760964948
##  [41]  0.497271510  0.449843159 -0.848775762 -1.147182073  0.345806314
##  [46]  0.712429910  0.358807807  1.386418838  0.848700937  1.431531414
##  [51]  1.028995087  1.889603063  0.178539914 -0.931313695 -0.157885545
##  [56] -1.034479287  0.814903596 -0.967592210 -0.646423203 -1.031097913
##  [61]  1.012508610  0.830899026  0.339712179 -0.487081048 -0.308557477
##  [66]  2.628643225  1.440297143  0.370609149  1.011299471 -0.719521142
##  [71] -2.204256171 -0.875847780 -0.182803871  1.454982068  0.951672894
##  [76] -0.084193829 -0.105019556  0.793754820  0.359673693  0.702568720
##  [81]  0.738714864 -0.791640056 -0.924459617 -2.188829775 -1.217664591
##  [86] -0.113462388 -0.448610736 -0.026409873 -0.029562012  0.547515984
##  [91]  0.249246315  0.269786088  0.857606481  1.044384022  0.078048040
##  [96]  1.826767358  2.535487860  0.958648831  0.651871556 -1.326317137
## [101] -0.863024298 -1.694919884  0.428903320  0.949023345  1.101248120
## [106]  0.969020809  2.571319697  1.097073289  2.406062099  3.039153274
## [111]  1.249777975  2.135263468  0.595822542  1.964001893  1.063195625
## [116]  1.308738982  0.164452921  0.772060309  0.480515551  2.313731813
## [121]  0.586367881  0.821151162 -1.283837828  2.136891063  0.046060676
## [126] -1.192182925 -0.615198781  0.775571069 -0.289266798 -0.298014894
## [131] -2.037803766 -2.058253261 -0.326273649  0.385105991  1.209314391
## [136] -0.065160402  2.334467051  2.352604180  1.193248716  2.347395232
## [141]  2.532856694  0.105614061  1.800803650  1.453752222  1.186045563
## [146] -0.461898370 -0.737351648  0.267153454  1.504638104  2.213862321
## [151]  0.688300452  1.224907443  2.583149433  0.792736505  1.482541286
## [156]  0.926229339  1.531657431  2.000256908  0.585096878 -0.196859960
## [161]  0.929270492  0.431738377  0.722352528  1.960689999  0.193659119
## [166]  0.530735676  2.178286382  2.734629384  2.604429048  2.934718476
## [171]  1.833690933  2.174430319  0.732749784  0.160451582  1.057609111
## [176] -0.252115568  0.688494155 -0.260449209 -1.024681055 -0.017274182
## [181]  0.578466907 -0.682446878  1.098520350  2.003139840  1.517300407
## [186]  2.188106855  1.761182249  1.185836932  0.344930942  1.013392706
## [191]  0.064673172 -0.249483969  0.460436878  0.331894176  2.245085434
## [196]  0.647315990  0.523908198  0.389529606  1.123226928  0.788167901
## [201]  1.096520643 -0.398925074 -0.120921393 -0.691496363  0.676592571
## [206] -1.805388468  1.559609098 -0.243064899  0.045276283 -1.898365165
## [211] -0.940204322 -1.929473218  0.530422647 -0.629244983 -0.609492025
## [216] -1.011877515 -0.273017437 -1.611431370 -1.537182882 -1.710921804
## [221] -0.877920476  0.665770994  0.165714575 -0.650828041 -0.793406642
## [226]  0.983621301 -0.776432286  0.169179685 -1.187775278 -1.286208196
## [231] -3.431067795 -0.356762324 -0.332976293  0.660739661  0.740816965
## [236] -0.220089489 -0.308649864 -1.016000070 -0.514958510 -0.366419173
## [241]  1.179740082  2.819694366  1.903573130  1.073784155  0.425320607
## [246]  1.338093471  0.578045818 -0.821233938 -0.282141322 -0.557374202
## [251] -2.090162609 -1.279272994 -0.974270278 -0.749447380 -1.074398976
## [256] -0.190689179 -1.023627691 -0.847809291 -1.278498663 -1.179979012
## [261] -0.592204081  1.016616724  1.690740927  2.178076820  1.185797922
## [266]  0.578184447 -0.204085336  0.226205484  0.915228004  0.690925870
## [271]  0.812397280 -1.088595469  0.402006579  1.614332024  1.025324528
## [276]  1.547182892  0.679887615  4.131904876  1.948039880  2.148843690
## [281]  0.472395798 -0.780902527  0.631961209 -0.756820300 -0.576300383
## [286] -0.576741758 -0.046839531 -0.838699282 -0.888703862 -1.063831326
## [291] -0.411168254 -0.374574747 -0.693606692  0.185382740 -0.416455123
## [296] -0.060793215  0.791690363  1.139969883  2.051071409
plot(y=yt_ar,x=yt_1_ar)

Berdasarkan scatterplot tersebut, terlihat bahwa terdapat hubungan positif antara \(Y_t\) dengan \(Y_{t-1}\). Hal ini sesuai dengan teori yang ada

cor(yt_ar,yt_1_ar)
## [1] 0.5926736

Korelasi antara \(Y_t\) dengan \(Y_{t-1}\) dari hasil simulasi mendekati perhitungan teoritis yaitu

\[ \rho_1=\frac{\phi_1}{1-\phi_2}=\frac{0.5}{1-0.2}=0.626 \]

Korelasi antara \(Y_t\) dengan \(Y_{t-2}\)

#Yt
yt_ar2 <- ar[-c(1,2)]
yt_ar2
##   [1]  1.165955987  0.938001648  4.040029883  1.814697744  2.125920865
##   [6]  0.863714547  2.048268102  1.545945122  1.694180277  1.601619567
##  [11]  0.371264692  0.004847193 -1.831910620 -2.693657731 -0.848960327
##  [16] -1.308949603  1.013994421  1.918290789  1.846186931  2.263708856
##  [21]  2.502983054  2.980469932  1.670192649  2.009644523  1.825961756
##  [26]  1.867757240  1.866634014  1.656435730  2.373983431  2.630476742
##  [31]  3.014418988  1.853562001  0.855327159  3.232502351  1.899226305
##  [36]  0.992684756  2.515564069  0.760964948  0.497271510  0.449843159
##  [41] -0.848775762 -1.147182073  0.345806314  0.712429910  0.358807807
##  [46]  1.386418838  0.848700937  1.431531414  1.028995087  1.889603063
##  [51]  0.178539914 -0.931313695 -0.157885545 -1.034479287  0.814903596
##  [56] -0.967592210 -0.646423203 -1.031097913  1.012508610  0.830899026
##  [61]  0.339712179 -0.487081048 -0.308557477  2.628643225  1.440297143
##  [66]  0.370609149  1.011299471 -0.719521142 -2.204256171 -0.875847780
##  [71] -0.182803871  1.454982068  0.951672894 -0.084193829 -0.105019556
##  [76]  0.793754820  0.359673693  0.702568720  0.738714864 -0.791640056
##  [81] -0.924459617 -2.188829775 -1.217664591 -0.113462388 -0.448610736
##  [86] -0.026409873 -0.029562012  0.547515984  0.249246315  0.269786088
##  [91]  0.857606481  1.044384022  0.078048040  1.826767358  2.535487860
##  [96]  0.958648831  0.651871556 -1.326317137 -0.863024298 -1.694919884
## [101]  0.428903320  0.949023345  1.101248120  0.969020809  2.571319697
## [106]  1.097073289  2.406062099  3.039153274  1.249777975  2.135263468
## [111]  0.595822542  1.964001893  1.063195625  1.308738982  0.164452921
## [116]  0.772060309  0.480515551  2.313731813  0.586367881  0.821151162
## [121] -1.283837828  2.136891063  0.046060676 -1.192182925 -0.615198781
## [126]  0.775571069 -0.289266798 -0.298014894 -2.037803766 -2.058253261
## [131] -0.326273649  0.385105991  1.209314391 -0.065160402  2.334467051
## [136]  2.352604180  1.193248716  2.347395232  2.532856694  0.105614061
## [141]  1.800803650  1.453752222  1.186045563 -0.461898370 -0.737351648
## [146]  0.267153454  1.504638104  2.213862321  0.688300452  1.224907443
## [151]  2.583149433  0.792736505  1.482541286  0.926229339  1.531657431
## [156]  2.000256908  0.585096878 -0.196859960  0.929270492  0.431738377
## [161]  0.722352528  1.960689999  0.193659119  0.530735676  2.178286382
## [166]  2.734629384  2.604429048  2.934718476  1.833690933  2.174430319
## [171]  0.732749784  0.160451582  1.057609111 -0.252115568  0.688494155
## [176] -0.260449209 -1.024681055 -0.017274182  0.578466907 -0.682446878
## [181]  1.098520350  2.003139840  1.517300407  2.188106855  1.761182249
## [186]  1.185836932  0.344930942  1.013392706  0.064673172 -0.249483969
## [191]  0.460436878  0.331894176  2.245085434  0.647315990  0.523908198
## [196]  0.389529606  1.123226928  0.788167901  1.096520643 -0.398925074
## [201] -0.120921393 -0.691496363  0.676592571 -1.805388468  1.559609098
## [206] -0.243064899  0.045276283 -1.898365165 -0.940204322 -1.929473218
## [211]  0.530422647 -0.629244983 -0.609492025 -1.011877515 -0.273017437
## [216] -1.611431370 -1.537182882 -1.710921804 -0.877920476  0.665770994
## [221]  0.165714575 -0.650828041 -0.793406642  0.983621301 -0.776432286
## [226]  0.169179685 -1.187775278 -1.286208196 -3.431067795 -0.356762324
## [231] -0.332976293  0.660739661  0.740816965 -0.220089489 -0.308649864
## [236] -1.016000070 -0.514958510 -0.366419173  1.179740082  2.819694366
## [241]  1.903573130  1.073784155  0.425320607  1.338093471  0.578045818
## [246] -0.821233938 -0.282141322 -0.557374202 -2.090162609 -1.279272994
## [251] -0.974270278 -0.749447380 -1.074398976 -0.190689179 -1.023627691
## [256] -0.847809291 -1.278498663 -1.179979012 -0.592204081  1.016616724
## [261]  1.690740927  2.178076820  1.185797922  0.578184447 -0.204085336
## [266]  0.226205484  0.915228004  0.690925870  0.812397280 -1.088595469
## [271]  0.402006579  1.614332024  1.025324528  1.547182892  0.679887615
## [276]  4.131904876  1.948039880  2.148843690  0.472395798 -0.780902527
## [281]  0.631961209 -0.756820300 -0.576300383 -0.576741758 -0.046839531
## [286] -0.838699282 -0.888703862 -1.063831326 -0.411168254 -0.374574747
## [291] -0.693606692  0.185382740 -0.416455123 -0.060793215  0.791690363
## [296]  1.139969883  2.051071409  1.731167996
#Yt-2
yt_2_ar <- ar[-c(299,300)] 
yt_2_ar
##   [1]  1.000000000  2.000000000  1.165955987  0.938001648  4.040029883
##   [6]  1.814697744  2.125920865  0.863714547  2.048268102  1.545945122
##  [11]  1.694180277  1.601619567  0.371264692  0.004847193 -1.831910620
##  [16] -2.693657731 -0.848960327 -1.308949603  1.013994421  1.918290789
##  [21]  1.846186931  2.263708856  2.502983054  2.980469932  1.670192649
##  [26]  2.009644523  1.825961756  1.867757240  1.866634014  1.656435730
##  [31]  2.373983431  2.630476742  3.014418988  1.853562001  0.855327159
##  [36]  3.232502351  1.899226305  0.992684756  2.515564069  0.760964948
##  [41]  0.497271510  0.449843159 -0.848775762 -1.147182073  0.345806314
##  [46]  0.712429910  0.358807807  1.386418838  0.848700937  1.431531414
##  [51]  1.028995087  1.889603063  0.178539914 -0.931313695 -0.157885545
##  [56] -1.034479287  0.814903596 -0.967592210 -0.646423203 -1.031097913
##  [61]  1.012508610  0.830899026  0.339712179 -0.487081048 -0.308557477
##  [66]  2.628643225  1.440297143  0.370609149  1.011299471 -0.719521142
##  [71] -2.204256171 -0.875847780 -0.182803871  1.454982068  0.951672894
##  [76] -0.084193829 -0.105019556  0.793754820  0.359673693  0.702568720
##  [81]  0.738714864 -0.791640056 -0.924459617 -2.188829775 -1.217664591
##  [86] -0.113462388 -0.448610736 -0.026409873 -0.029562012  0.547515984
##  [91]  0.249246315  0.269786088  0.857606481  1.044384022  0.078048040
##  [96]  1.826767358  2.535487860  0.958648831  0.651871556 -1.326317137
## [101] -0.863024298 -1.694919884  0.428903320  0.949023345  1.101248120
## [106]  0.969020809  2.571319697  1.097073289  2.406062099  3.039153274
## [111]  1.249777975  2.135263468  0.595822542  1.964001893  1.063195625
## [116]  1.308738982  0.164452921  0.772060309  0.480515551  2.313731813
## [121]  0.586367881  0.821151162 -1.283837828  2.136891063  0.046060676
## [126] -1.192182925 -0.615198781  0.775571069 -0.289266798 -0.298014894
## [131] -2.037803766 -2.058253261 -0.326273649  0.385105991  1.209314391
## [136] -0.065160402  2.334467051  2.352604180  1.193248716  2.347395232
## [141]  2.532856694  0.105614061  1.800803650  1.453752222  1.186045563
## [146] -0.461898370 -0.737351648  0.267153454  1.504638104  2.213862321
## [151]  0.688300452  1.224907443  2.583149433  0.792736505  1.482541286
## [156]  0.926229339  1.531657431  2.000256908  0.585096878 -0.196859960
## [161]  0.929270492  0.431738377  0.722352528  1.960689999  0.193659119
## [166]  0.530735676  2.178286382  2.734629384  2.604429048  2.934718476
## [171]  1.833690933  2.174430319  0.732749784  0.160451582  1.057609111
## [176] -0.252115568  0.688494155 -0.260449209 -1.024681055 -0.017274182
## [181]  0.578466907 -0.682446878  1.098520350  2.003139840  1.517300407
## [186]  2.188106855  1.761182249  1.185836932  0.344930942  1.013392706
## [191]  0.064673172 -0.249483969  0.460436878  0.331894176  2.245085434
## [196]  0.647315990  0.523908198  0.389529606  1.123226928  0.788167901
## [201]  1.096520643 -0.398925074 -0.120921393 -0.691496363  0.676592571
## [206] -1.805388468  1.559609098 -0.243064899  0.045276283 -1.898365165
## [211] -0.940204322 -1.929473218  0.530422647 -0.629244983 -0.609492025
## [216] -1.011877515 -0.273017437 -1.611431370 -1.537182882 -1.710921804
## [221] -0.877920476  0.665770994  0.165714575 -0.650828041 -0.793406642
## [226]  0.983621301 -0.776432286  0.169179685 -1.187775278 -1.286208196
## [231] -3.431067795 -0.356762324 -0.332976293  0.660739661  0.740816965
## [236] -0.220089489 -0.308649864 -1.016000070 -0.514958510 -0.366419173
## [241]  1.179740082  2.819694366  1.903573130  1.073784155  0.425320607
## [246]  1.338093471  0.578045818 -0.821233938 -0.282141322 -0.557374202
## [251] -2.090162609 -1.279272994 -0.974270278 -0.749447380 -1.074398976
## [256] -0.190689179 -1.023627691 -0.847809291 -1.278498663 -1.179979012
## [261] -0.592204081  1.016616724  1.690740927  2.178076820  1.185797922
## [266]  0.578184447 -0.204085336  0.226205484  0.915228004  0.690925870
## [271]  0.812397280 -1.088595469  0.402006579  1.614332024  1.025324528
## [276]  1.547182892  0.679887615  4.131904876  1.948039880  2.148843690
## [281]  0.472395798 -0.780902527  0.631961209 -0.756820300 -0.576300383
## [286] -0.576741758 -0.046839531 -0.838699282 -0.888703862 -1.063831326
## [291] -0.411168254 -0.374574747 -0.693606692  0.185382740 -0.416455123
## [296] -0.060793215  0.791690363  1.139969883
plot(y=yt_ar2,x=yt_2_ar)

Berdasarkan scatterplot tersebut, terlihat bahwa terdapat hubungan positif antara \(Y_t\) dengan \(Y_{t-2}\). Hal ini sesuai dengan teori yang ada

cor(yt_ar2,yt_2_ar)
## [1] 0.4820466

Korelasi antara \(Y_t\) dengan \(Y_{t-2}\) dari hasil simulasi mendekati perhitungan teoritis yaitu

\[ \rho_1=\frac{\phi_1^2}{1-\phi_2}+\phi_2=\frac{0.5^2}{1-0.2}+0.2=0.5125 \]

Korelasi antara \(Y_t\) dengan \(Y_{t-3}\)

#Yt
yt_ar3 <- ar[-c(1,2,3)] 
yt_ar3
##   [1]  0.938001648  4.040029883  1.814697744  2.125920865  0.863714547
##   [6]  2.048268102  1.545945122  1.694180277  1.601619567  0.371264692
##  [11]  0.004847193 -1.831910620 -2.693657731 -0.848960327 -1.308949603
##  [16]  1.013994421  1.918290789  1.846186931  2.263708856  2.502983054
##  [21]  2.980469932  1.670192649  2.009644523  1.825961756  1.867757240
##  [26]  1.866634014  1.656435730  2.373983431  2.630476742  3.014418988
##  [31]  1.853562001  0.855327159  3.232502351  1.899226305  0.992684756
##  [36]  2.515564069  0.760964948  0.497271510  0.449843159 -0.848775762
##  [41] -1.147182073  0.345806314  0.712429910  0.358807807  1.386418838
##  [46]  0.848700937  1.431531414  1.028995087  1.889603063  0.178539914
##  [51] -0.931313695 -0.157885545 -1.034479287  0.814903596 -0.967592210
##  [56] -0.646423203 -1.031097913  1.012508610  0.830899026  0.339712179
##  [61] -0.487081048 -0.308557477  2.628643225  1.440297143  0.370609149
##  [66]  1.011299471 -0.719521142 -2.204256171 -0.875847780 -0.182803871
##  [71]  1.454982068  0.951672894 -0.084193829 -0.105019556  0.793754820
##  [76]  0.359673693  0.702568720  0.738714864 -0.791640056 -0.924459617
##  [81] -2.188829775 -1.217664591 -0.113462388 -0.448610736 -0.026409873
##  [86] -0.029562012  0.547515984  0.249246315  0.269786088  0.857606481
##  [91]  1.044384022  0.078048040  1.826767358  2.535487860  0.958648831
##  [96]  0.651871556 -1.326317137 -0.863024298 -1.694919884  0.428903320
## [101]  0.949023345  1.101248120  0.969020809  2.571319697  1.097073289
## [106]  2.406062099  3.039153274  1.249777975  2.135263468  0.595822542
## [111]  1.964001893  1.063195625  1.308738982  0.164452921  0.772060309
## [116]  0.480515551  2.313731813  0.586367881  0.821151162 -1.283837828
## [121]  2.136891063  0.046060676 -1.192182925 -0.615198781  0.775571069
## [126] -0.289266798 -0.298014894 -2.037803766 -2.058253261 -0.326273649
## [131]  0.385105991  1.209314391 -0.065160402  2.334467051  2.352604180
## [136]  1.193248716  2.347395232  2.532856694  0.105614061  1.800803650
## [141]  1.453752222  1.186045563 -0.461898370 -0.737351648  0.267153454
## [146]  1.504638104  2.213862321  0.688300452  1.224907443  2.583149433
## [151]  0.792736505  1.482541286  0.926229339  1.531657431  2.000256908
## [156]  0.585096878 -0.196859960  0.929270492  0.431738377  0.722352528
## [161]  1.960689999  0.193659119  0.530735676  2.178286382  2.734629384
## [166]  2.604429048  2.934718476  1.833690933  2.174430319  0.732749784
## [171]  0.160451582  1.057609111 -0.252115568  0.688494155 -0.260449209
## [176] -1.024681055 -0.017274182  0.578466907 -0.682446878  1.098520350
## [181]  2.003139840  1.517300407  2.188106855  1.761182249  1.185836932
## [186]  0.344930942  1.013392706  0.064673172 -0.249483969  0.460436878
## [191]  0.331894176  2.245085434  0.647315990  0.523908198  0.389529606
## [196]  1.123226928  0.788167901  1.096520643 -0.398925074 -0.120921393
## [201] -0.691496363  0.676592571 -1.805388468  1.559609098 -0.243064899
## [206]  0.045276283 -1.898365165 -0.940204322 -1.929473218  0.530422647
## [211] -0.629244983 -0.609492025 -1.011877515 -0.273017437 -1.611431370
## [216] -1.537182882 -1.710921804 -0.877920476  0.665770994  0.165714575
## [221] -0.650828041 -0.793406642  0.983621301 -0.776432286  0.169179685
## [226] -1.187775278 -1.286208196 -3.431067795 -0.356762324 -0.332976293
## [231]  0.660739661  0.740816965 -0.220089489 -0.308649864 -1.016000070
## [236] -0.514958510 -0.366419173  1.179740082  2.819694366  1.903573130
## [241]  1.073784155  0.425320607  1.338093471  0.578045818 -0.821233938
## [246] -0.282141322 -0.557374202 -2.090162609 -1.279272994 -0.974270278
## [251] -0.749447380 -1.074398976 -0.190689179 -1.023627691 -0.847809291
## [256] -1.278498663 -1.179979012 -0.592204081  1.016616724  1.690740927
## [261]  2.178076820  1.185797922  0.578184447 -0.204085336  0.226205484
## [266]  0.915228004  0.690925870  0.812397280 -1.088595469  0.402006579
## [271]  1.614332024  1.025324528  1.547182892  0.679887615  4.131904876
## [276]  1.948039880  2.148843690  0.472395798 -0.780902527  0.631961209
## [281] -0.756820300 -0.576300383 -0.576741758 -0.046839531 -0.838699282
## [286] -0.888703862 -1.063831326 -0.411168254 -0.374574747 -0.693606692
## [291]  0.185382740 -0.416455123 -0.060793215  0.791690363  1.139969883
## [296]  2.051071409  1.731167996
#Yt-3
yt_3_ar <- ar[-c(298,299,300)] 
yt_3_ar
##   [1]  1.000000000  2.000000000  1.165955987  0.938001648  4.040029883
##   [6]  1.814697744  2.125920865  0.863714547  2.048268102  1.545945122
##  [11]  1.694180277  1.601619567  0.371264692  0.004847193 -1.831910620
##  [16] -2.693657731 -0.848960327 -1.308949603  1.013994421  1.918290789
##  [21]  1.846186931  2.263708856  2.502983054  2.980469932  1.670192649
##  [26]  2.009644523  1.825961756  1.867757240  1.866634014  1.656435730
##  [31]  2.373983431  2.630476742  3.014418988  1.853562001  0.855327159
##  [36]  3.232502351  1.899226305  0.992684756  2.515564069  0.760964948
##  [41]  0.497271510  0.449843159 -0.848775762 -1.147182073  0.345806314
##  [46]  0.712429910  0.358807807  1.386418838  0.848700937  1.431531414
##  [51]  1.028995087  1.889603063  0.178539914 -0.931313695 -0.157885545
##  [56] -1.034479287  0.814903596 -0.967592210 -0.646423203 -1.031097913
##  [61]  1.012508610  0.830899026  0.339712179 -0.487081048 -0.308557477
##  [66]  2.628643225  1.440297143  0.370609149  1.011299471 -0.719521142
##  [71] -2.204256171 -0.875847780 -0.182803871  1.454982068  0.951672894
##  [76] -0.084193829 -0.105019556  0.793754820  0.359673693  0.702568720
##  [81]  0.738714864 -0.791640056 -0.924459617 -2.188829775 -1.217664591
##  [86] -0.113462388 -0.448610736 -0.026409873 -0.029562012  0.547515984
##  [91]  0.249246315  0.269786088  0.857606481  1.044384022  0.078048040
##  [96]  1.826767358  2.535487860  0.958648831  0.651871556 -1.326317137
## [101] -0.863024298 -1.694919884  0.428903320  0.949023345  1.101248120
## [106]  0.969020809  2.571319697  1.097073289  2.406062099  3.039153274
## [111]  1.249777975  2.135263468  0.595822542  1.964001893  1.063195625
## [116]  1.308738982  0.164452921  0.772060309  0.480515551  2.313731813
## [121]  0.586367881  0.821151162 -1.283837828  2.136891063  0.046060676
## [126] -1.192182925 -0.615198781  0.775571069 -0.289266798 -0.298014894
## [131] -2.037803766 -2.058253261 -0.326273649  0.385105991  1.209314391
## [136] -0.065160402  2.334467051  2.352604180  1.193248716  2.347395232
## [141]  2.532856694  0.105614061  1.800803650  1.453752222  1.186045563
## [146] -0.461898370 -0.737351648  0.267153454  1.504638104  2.213862321
## [151]  0.688300452  1.224907443  2.583149433  0.792736505  1.482541286
## [156]  0.926229339  1.531657431  2.000256908  0.585096878 -0.196859960
## [161]  0.929270492  0.431738377  0.722352528  1.960689999  0.193659119
## [166]  0.530735676  2.178286382  2.734629384  2.604429048  2.934718476
## [171]  1.833690933  2.174430319  0.732749784  0.160451582  1.057609111
## [176] -0.252115568  0.688494155 -0.260449209 -1.024681055 -0.017274182
## [181]  0.578466907 -0.682446878  1.098520350  2.003139840  1.517300407
## [186]  2.188106855  1.761182249  1.185836932  0.344930942  1.013392706
## [191]  0.064673172 -0.249483969  0.460436878  0.331894176  2.245085434
## [196]  0.647315990  0.523908198  0.389529606  1.123226928  0.788167901
## [201]  1.096520643 -0.398925074 -0.120921393 -0.691496363  0.676592571
## [206] -1.805388468  1.559609098 -0.243064899  0.045276283 -1.898365165
## [211] -0.940204322 -1.929473218  0.530422647 -0.629244983 -0.609492025
## [216] -1.011877515 -0.273017437 -1.611431370 -1.537182882 -1.710921804
## [221] -0.877920476  0.665770994  0.165714575 -0.650828041 -0.793406642
## [226]  0.983621301 -0.776432286  0.169179685 -1.187775278 -1.286208196
## [231] -3.431067795 -0.356762324 -0.332976293  0.660739661  0.740816965
## [236] -0.220089489 -0.308649864 -1.016000070 -0.514958510 -0.366419173
## [241]  1.179740082  2.819694366  1.903573130  1.073784155  0.425320607
## [246]  1.338093471  0.578045818 -0.821233938 -0.282141322 -0.557374202
## [251] -2.090162609 -1.279272994 -0.974270278 -0.749447380 -1.074398976
## [256] -0.190689179 -1.023627691 -0.847809291 -1.278498663 -1.179979012
## [261] -0.592204081  1.016616724  1.690740927  2.178076820  1.185797922
## [266]  0.578184447 -0.204085336  0.226205484  0.915228004  0.690925870
## [271]  0.812397280 -1.088595469  0.402006579  1.614332024  1.025324528
## [276]  1.547182892  0.679887615  4.131904876  1.948039880  2.148843690
## [281]  0.472395798 -0.780902527  0.631961209 -0.756820300 -0.576300383
## [286] -0.576741758 -0.046839531 -0.838699282 -0.888703862 -1.063831326
## [291] -0.411168254 -0.374574747 -0.693606692  0.185382740 -0.416455123
## [296] -0.060793215  0.791690363
plot(y=yt_ar3,x=yt_3_ar)

Berdasarkan scatterplot tersebut, terlihat bahwa terdapat hubungan positif antara \(Y_t\) dengan \(Y_{t-3}\). Hal ini sesuai dengan teori yang ada

cor(yt_ar3,yt_3_ar)
## [1] 0.3101654

Korelasi antara \(Y_t\) dengan \(Y_{t-1}\) dari hasil simulasi mendekati perhitungan teoritis yaitu

\[ \rho_1=\frac{\phi_1^3+\phi_1\phi_2}{1-\phi_2}+\phi_1\phi_2=\frac{0.5^2+(0.5)(0.2)}{1-0.2}+(0.5)(0.2)=0.38125 \]

Fungsi pembangkitan ARMA

Bentuk umum data berpola ARMA.

\[ y_{t} = c + \sum_{i=1}^p \phi_{i}y_{t-i} + \sum_{j=1}^q e_{t-j}+ e_{t} \]

Pembangkitan Proses ARMA(2,2)

Pembangkitan proses ARMA(2,2) secara manual

set.seed(035)
n = length(wn)
phi1 = 0.5
phi2 = 0.2

theta1 = 0.4
theta2 = 0.6

y.arma=c(1:n)
for (i in 5:n){y.arma[i] = phi1*y.arma[i-1] +phi2*y.arma[i-2] + theta1*wn[i-1] + phi2*y.arma[i-2]+wn[i]}
y.arma
##   [1]  1.00000000  2.00000000  3.00000000  4.00000000  6.51984732  5.80214128
##   [7]  5.76240857  4.80410177  5.67336680  5.58388293  5.71246954  5.73974999
##  [13]  4.56461783  3.76974738  1.60169004 -0.23336275  0.67677656  0.24500555
##  [19]  2.09317953  3.55298000  3.96723786  4.63546523  5.28930189  6.17583017
##  [25]  5.39349157  5.61727649  5.68451752  5.83685720  5.98093763  5.90180419
##  [31]  6.65554282  7.26966647  7.96631345  7.20103404  6.04080763  8.06520875
##  [37]  7.53448767  6.43466235  7.62913112  6.34882703  5.56160057  5.21481600
##  [43]  3.67850235  2.64315410  3.55702536  4.04039849  3.68402625  4.49607411
##  [49]  4.23118909  4.67741335  4.46663037  5.25047544  3.87534893  2.25053612
##  [55]  2.38806925  1.43380062  2.72813885  1.31492966  0.95585329  0.35928752
##  [61]  2.01358014  2.34430626  1.91169185  0.95915586  0.78204851  3.60184102
##  [67]  3.45356221  2.36732425  2.75291525  1.23926880 -0.84567207 -0.37564618
##  [73]  0.31795315  2.00866016  2.08087540  1.09717213  0.78726833  1.59430349
##  [79]  1.44110062  1.71577269  1.89541472  0.45870351 -0.20946941 -1.76007828
##  [85] -1.52949347 -0.51098529 -0.64238231 -0.36433595 -0.27752064  0.31243029
##  [91]  0.25363920  0.28001174  0.92858962  1.40706874  0.68395438  2.23740511
##  [97]  3.63032549  2.67827405  2.18693736  0.18697545 -0.09957045 -1.10523537
## [103]  0.45726454  1.43968103  1.87312438  1.95740900  3.68595075  2.99017212
## [109]  4.15977159  5.42996681  4.27456399  4.91140811  3.80478239  4.81728645
## [115]  4.38820153  4.49016820  3.45154533  3.66890372  3.44789923  5.13521100
## [121]  4.04778885  3.87655923  1.77179651  4.32642690  3.15214666  1.35780570
## [127]  1.25440547  2.48060428  1.71669457  1.32048826 -0.60741929 -1.48763992
## [133] -0.26827330  0.67486634  1.69609736  0.80396287  2.90686924  3.82349625
## [139]  3.10391013  4.18162489  4.96498585  2.97305328  4.06182893  4.24893347
## [145]  4.06109806  2.42405431  1.55458617  2.17767913  3.52048932  4.64684157
## [151]  3.57530322  3.79654966  5.33662564  4.17632723  4.49482914  4.17217411
## [157]  4.66661777  5.36017466  4.24504431  3.08858701  3.79720841  3.50478657
## [163]  3.59449594  4.84058036  3.53219859  3.37163700  4.98959190  6.13246450
## [169]  6.47926171  7.09877756  6.42077058  6.65871583  5.44471905  4.45655506
## [175]  4.98067476  3.79228231  4.16623700  3.28697030  2.05611540  2.47713989
## [181]  3.07191879  1.87540594  3.10323070  4.42176693  4.38434978  5.10812091
## [187]  5.08300058  4.59784058  3.67894632  4.04227965  3.22321293  2.53961548
## [193]  2.93753750  2.86508517  4.65523757  3.72686768  3.26011976  3.01941250
## [199]  3.63667956  3.50422549  3.74403528  2.36000539  2.09492623  1.38390942
## [205]  2.35594998  0.14476329  2.53959226  1.59670362  1.40435892 -0.58957465
## [211] -0.48207688 -1.55659712  0.28019160 -0.31782467 -0.65121442 -1.19440121
## [217] -0.73537965 -1.97606957 -2.46806921 -2.91525201 -2.40789432 -0.80914157
## [223] -0.78054910 -1.57740544 -1.94879371 -0.29532301 -1.43254451 -0.91755453
## [229] -2.00460511 -2.54231233 -4.91386944 -2.87800990 -2.22652901 -1.15324082
## [235] -0.63075751 -1.30850403 -1.54238190 -2.25095721 -2.01472276 -1.79157557
## [241] -0.19803148  2.07383874  2.13672797  1.55906937  0.96516327  1.81997128
## [247]  1.48425644  0.02181518  0.06632643 -0.20502087 -1.93184981 -1.87266900
## [253] -1.67476242 -1.55954696 -1.95708274 -1.30788886 -1.95162091 -2.08218493
## [259] -2.59075236 -2.75936536 -2.31096560 -0.60912031  0.69141281  1.75179065
## [265]  1.36282498  0.83524340  0.05228260  0.28071506  1.08925740  1.18216243
## [271]  1.38590123 -0.35360820  0.50818954  2.05722926  2.02206678  2.60068220
## [277]  2.09506076  5.45082025  4.70255415  4.77849192  3.41801070  1.77687935
## [283]  2.60482960  1.46771947  1.08486094  0.86257776  1.16713368  0.37138335
## [289] -0.08741364 -0.53088754 -0.18261686 -0.14049253 -0.54986842  0.10633555
## [295] -0.29436433 -0.14246021  0.76054527  1.44172310  2.65034139  2.90859761
set.seed(1234)
n = length(wn)
phi1 = 0.7 #ARMA 1 1
theta1 = 0.5

y.arma=c(1:n)
for (i in 3:n){y.arma[i] = phi1*y.arma[i-1] + theta1*wn[i-1]+wn[i]}
y.arma
##   [1]  1.000000000  2.000000000  1.432396579  0.940679254  3.973825166
##   [6]  4.057679020  3.054482567  1.781235370  2.156998697  2.454580578
##  [11]  2.404294581  2.384123659  1.123175616 -0.099076708 -2.228495384
##  [16] -4.292912206 -3.030123812 -2.034699230  0.241102881  2.760986160
##  [21]  3.453474713  3.716510858  4.081927457  4.634531474  3.561651420
##  [26]  2.911290742  2.814231591  2.766360053  2.780438809  2.579655962
##  [31]  3.152981574  3.905504364  4.514335926  3.592484272  1.750529931
##  [36]  3.322328504  3.654602836  2.010747967  2.745185574  2.045964079
##  [41]  0.698174058  0.344574366 -0.907442380 -2.034548311 -0.741412727
##  [46]  0.794550511  0.874098530  1.643113718  1.766174036  2.008083981
##  [51]  1.914096569  2.500411431  1.322626984 -0.958695693 -1.098275798
##  [56] -1.402035174 -0.002341160 -0.487926789 -1.251230645 -1.553033229
##  [61]  0.313035012  1.578659916  1.092255036 -0.197657945 -0.682878421
##  [66]  2.335843584  3.262946621  1.502638080  1.152148090 -0.223821311
##  [71] -2.853076765 -2.650346948 -0.974179344  1.387613645  2.092848966
##  [76]  0.744338903 -0.157733333  0.626061420  0.853594871  0.953397417
##  [81]  1.164864411 -0.328358262 -1.556988961 -2.996355508 -2.819942614
##  [86] -1.010002857 -0.388780692 -0.125731824  0.095646781  0.671214247
##  [91]  0.735040181  0.540888223  1.069315798  1.646576709  0.817750210
##  [96]  1.843459048  3.686349173  2.709243137  1.224695479 -1.153971062
## [101] -2.060011124 -2.605272114 -0.873794512  1.186383563  1.908202109
## [106]  1.834811448  3.265223722  2.836545718  3.137648157  4.484692034
## [111]  3.196627125  2.764677273  1.664781217  2.043502387  2.012000805
## [116]  1.773756439  0.731244208  0.588679150  0.687713244  2.431258652
## [121]  1.994810909  1.128287927 -0.989275007  1.016243747  1.253043206
## [126] -1.148269877 -1.653404105  0.150064444  0.211836057 -0.437216757
## [131] -2.291242544 -3.499089660 -1.828823227  0.234924076  1.726409712
## [136]  1.002656066  2.453624222  3.978531878  2.934226898  3.109235475
## [141]  3.937099186  1.685930765  1.606430150  2.277441330  1.959331446
## [146]  0.075364777 -1.363692030 -0.598181256  1.463909304  3.192114944
## [151]  2.218978420  1.631490482  3.194071335  2.408548045  1.883616929
## [156]  1.629714818  1.926040574  2.783427979  1.751627685 -0.024001933
## [161]  0.449149853  0.776220569  0.867221201  2.280535521  1.421801508
## [166]  0.571450979  2.295086464  4.082992943  4.429221668  4.586761783
## [171]  3.598968171  3.112641820  1.792966290  0.253665248  0.687994350
## [176]  0.084002287  0.255326497 -0.074029566 -1.361112564 -0.921700249
## [181]  0.420428128 -0.277905701  0.645403670  2.704176814  2.984134707
## [186]  3.265736186  3.164098412  2.264327695  0.918617631  0.946680203
## [191]  0.453546698 -0.422521093  0.034229915  0.461655585  2.385996146
## [196]  2.122117225  0.965912393  0.549867541  1.207643919  1.405839502
## [201]  1.536203216  0.209418929 -0.546579223 -1.004237600  0.067933386
## [206] -1.434569595  0.320093360  0.725766007  0.032027241 -1.922527802
## [211] -2.282041621 -2.677165656 -0.730664851 -0.178426998 -0.780133793
## [216] -1.327853193 -0.865318762 -1.700860420 -2.503739578 -2.711093648
## [221] -1.922810596  0.243436676  0.902276643 -0.231039291 -1.096282804
## [226]  0.492524500 -0.009549343 -0.200793777 -1.077298523 -2.038804792
## [231] -4.340650243 -2.697646278 -0.548727360  0.780280334  1.472528763
## [236]  0.546645426 -0.325439666 -1.218849262 -1.207251606 -0.723430279
## [241]  1.006670224  3.740748001  4.027855611  2.506446610  1.041255889
## [246]  1.393412410  1.254661817 -0.587644789 -1.087422639 -1.006819359
## [251] -2.585849172 -2.810334892 -1.945194108 -1.326394147 -1.436525955
## [256] -0.761578999 -0.998308712 -1.353375362 -1.746160038 -1.918414088
## [261] -1.274988615  0.782965116  2.623306246  3.616134074  2.854596685
## [266]  1.427193465  0.043533342 -0.122083970  0.863789181  1.214194363
## [271]  1.227860184 -0.631532782 -0.474737731  1.690643845  2.136731806
## [276]  2.276245088  1.650429936  4.488441077  4.629280918  3.461994377
## [281]  1.605983429 -0.818497775 -0.368449712 -0.710568540 -1.279990653
## [286] -1.195362201 -0.548575870 -0.905538562 -1.443828891 -1.692412920
## [291] -1.112070631 -0.585429706 -0.811998639 -0.173340846 -0.188213229
## [296] -0.206604040  0.815934067  1.780126189  2.946978399  3.201897391

Pembangkitan ARMA(p,q) juga dapat dilakukan dengan fungsi arima.sim sebagai berikut.

arma22 <- arima.sim(list(order=c(2,0,2), ar = c(0.5,0.2), ma =c(0.4,0.6)), n=300)
arma22
## Time Series:
## Start = 1 
## End = 300 
## Frequency = 1 
##   [1] -2.75189059 -1.74814288 -2.98064692 -1.12111691 -1.75293106 -1.33898765
##   [7] -2.09046996 -3.56829323 -4.32225209 -6.49932813 -7.02769509 -6.95242810
##  [13] -6.26996407 -3.43890672 -3.74182891 -2.97181976 -3.49823015 -3.96328709
##  [19] -4.21591372 -4.99194225 -5.61517562 -5.49498965 -5.32810268 -6.08211738
##  [25] -5.70927763 -6.49640104 -6.19781946 -5.63181804 -4.16631811 -1.43386858
##  [31] -1.32659085  1.33518960 -0.57718012  1.13545868  2.56923465  2.89049818
##  [37]  2.80495292  1.68426168  2.77538382  1.29220743  3.17981524  3.04188012
##  [43]  3.84589813  3.47054592  2.25362466  1.27634579  1.31729358  3.02358708
##  [49]  2.83893413  1.81428668  0.10302896 -0.45121970 -0.85290753 -0.66635425
##  [55] -0.93510416 -2.14779642 -2.08562341 -1.51503473 -0.24121274  0.91556687
##  [61]  0.64537308  0.48311177 -1.14217407 -1.12039092 -1.27141453  0.91636167
##  [67]  2.04091439  2.13232979  2.23257264  0.25301429  1.21071226  1.29939237
##  [73]  3.92904462  4.07112121  3.78513073  2.83160983  1.41191959  0.28488816
##  [79] -0.04006883 -1.28812485 -0.74220308 -0.74424287 -0.32976863 -0.31752860
##  [85] -0.98342470 -2.04217397 -1.20184647 -1.31314616  0.45270778 -0.93468943
##  [91] -0.20680752 -0.29613748  0.15497575  0.22025744 -0.73310547  1.30806278
##  [97]  1.61203256  4.42693491  3.79591780  3.27848542  0.68061022 -0.62425847
## [103] -1.11211846  0.04164014  0.59240357 -0.15810424  0.39101368 -1.92189820
## [109] -1.50741039 -2.59060462 -3.89098912 -2.51252738 -3.45825773 -2.26278511
## [115] -0.93523383  0.07413764  0.83334886  1.28389670  1.34833602  3.06177019
## [121]  2.98115137  3.71727357  3.17046413  2.39423349  1.98646516  2.92352912
## [127]  1.69753466  2.18824295  2.31910758  1.98048956  1.12411345 -0.47375475
## [133] -1.38212484 -2.31108442 -2.26562282 -2.62211380 -2.26938378 -1.57393069
## [139] -0.56321701  1.57589801  1.65267412  1.80012273  2.53204975  3.72627716
## [145]  3.97712776  3.44105725  0.58660225  1.46428641 -0.51695507 -0.57765858
## [151]  1.69949100  1.51248377  2.98314953 -0.81043866 -1.02122299 -1.37591544
## [157] -0.14779506  1.31440815  3.22462748  4.38519006  3.98666624  4.07252161
## [163]  2.61160764  1.92537895 -1.70502573 -2.72222986 -3.24361938 -0.27688538
## [169]  0.87342985  2.50264542  1.00860632  1.15325179 -1.81437043 -0.92501023
## [175] -1.18146222 -0.02037563  0.94652009  1.17246770  2.08111275  3.60870710
## [181]  4.52620181  4.56792960  2.75523948  2.28308227  0.79090755  2.43630393
## [187]  0.12650863  0.38802680 -0.48922578 -0.39939179 -0.71118176 -1.07369267
## [193] -0.53512569  0.48185240  1.52990415  3.93599432  4.75299655  5.28489601
## [199]  3.75245965  5.76106696  5.08023491  5.03046078  3.85049062  2.27094879
## [205]  1.61300623  0.02267186 -0.08744134 -0.23338993 -1.01395405 -4.02632785
## [211] -4.41061552 -5.02289664 -2.94041531 -2.16023161 -0.87458164 -1.76626866
## [217] -0.53794493 -0.27753067  0.71955739  2.19354067  2.33905070  2.84874980
## [223]  2.50865574  2.52684453  3.16087589  3.22420516  3.72442687  1.90727460
## [229]  1.27139490  1.66409882  0.23091397  1.10296539  0.37155340  1.69901525
## [235]  1.20826458  1.54849208 -0.89323198 -0.40844829 -1.97195019 -1.36977976
## [241] -2.76244287 -1.88853615 -1.38886217 -0.87915921  1.38576118  1.73484421
## [247]  3.45643730  4.90637915  3.88230417  4.70024354  4.04594276  3.83665310
## [253]  3.63604751  1.69745094  1.83280517  0.13589632  1.24990445 -0.25440835
## [259]  0.60581161 -0.95359799 -0.74837042 -2.72398269 -2.15183291 -1.51561139
## [265] -0.53368698 -1.67162994 -2.15962923 -1.06604857  1.13495225  0.89677762
## [271]  0.92454452  0.14354987  0.49726828  0.03722489 -0.87570167 -1.33912012
## [277] -0.47863083 -0.18724669 -0.22304216 -0.89877996  0.52922646 -0.01897051
## [283]  1.64938777  2.32971329  2.98499263  2.59721428  1.95311423  0.73468623
## [289]  1.76477012  1.07548761  3.11749005  1.74249123  1.55297139  0.67230168
## [295]  0.33991628 -0.10447830 -1.75292012 -1.80251894 -2.90523171 -0.99909951

Karakteristik ARMA(2,2)

Plot Time Series

par(mfrow = c(1, 2))
ts.plot(y.arma)
ts.plot(arma22)

par(mfrow = c(1, 1))

Berdasarkan plot time series tersebut, terlihat bahwa model ARMA(2,2) cenderung stasioner dalam rataan

Plot ACF

par(mfrow = c(1, 2))
acf(y.arma)
acf(arma22)

par(mfrow = c(1, 1))

Berdasarkan plot ACF tersebut, terlihat bahwa model ARMA(2,2) hasil simulasi memiliki plot ACF yang tails off, sesuai dengan teori yang ada

Plot PACF

par(mfrow = c(1, 2))
pacf(y.arma)
pacf(arma22)

par(mfrow = c(1, 1))

Berdasarkan plot PACF tersebut, terlihat bahwa model ARMA(2,2) hasil simulasi memiliki plot PACF yang tails off, sesuai dengan teori

Plot EACF

TSA::eacf(y.arma)
## AR/MA
##   0 1 2 3 4 5 6 7 8 9 10 11 12 13
## 0 x x x x o o o o o o o  o  o  x 
## 1 x o o o o o o o o o o  o  o  o 
## 2 x x o o o o o o o o o  o  o  o 
## 3 x x x o o o o o o o o  o  o  o 
## 4 x x x o o o o o o o o  o  o  o 
## 5 x o o o x o o o o o o  o  o  o 
## 6 x o x x o x o o o o o  o  o  o 
## 7 x x o x o x o o o o o  o  o  o
TSA::eacf(arma22)
## AR/MA
##   0 1 2 3 4 5 6 7 8 9 10 11 12 13
## 0 x x x x x x x o o o o  o  x  o 
## 1 o x o o o o x o o o o  o  o  o 
## 2 x x o o o o o o o o o  o  o  o 
## 3 x x x x o o o o o o o  o  o  o 
## 4 x x x x o o o o o o o  o  o  o 
## 5 x x x x x x x o o o o  o  o  o 
## 6 o o x o x x o o o o o  o  o  o 
## 7 x o x x x x o x o o o  o  o  o

Berdasarkan pola segitiga nol pada plot EACF, terlihat bahwa segitiga nol berada pada ordo AR(2) dan ordo MA(2)

Scatterplot Antar Lag

Korelasi antara \(Y_t\) dengan \(Y_{t-1}\)

#Yt
yt_arma <- arma22[-1]
yt_arma
##   [1] -1.74814288 -2.98064692 -1.12111691 -1.75293106 -1.33898765 -2.09046996
##   [7] -3.56829323 -4.32225209 -6.49932813 -7.02769509 -6.95242810 -6.26996407
##  [13] -3.43890672 -3.74182891 -2.97181976 -3.49823015 -3.96328709 -4.21591372
##  [19] -4.99194225 -5.61517562 -5.49498965 -5.32810268 -6.08211738 -5.70927763
##  [25] -6.49640104 -6.19781946 -5.63181804 -4.16631811 -1.43386858 -1.32659085
##  [31]  1.33518960 -0.57718012  1.13545868  2.56923465  2.89049818  2.80495292
##  [37]  1.68426168  2.77538382  1.29220743  3.17981524  3.04188012  3.84589813
##  [43]  3.47054592  2.25362466  1.27634579  1.31729358  3.02358708  2.83893413
##  [49]  1.81428668  0.10302896 -0.45121970 -0.85290753 -0.66635425 -0.93510416
##  [55] -2.14779642 -2.08562341 -1.51503473 -0.24121274  0.91556687  0.64537308
##  [61]  0.48311177 -1.14217407 -1.12039092 -1.27141453  0.91636167  2.04091439
##  [67]  2.13232979  2.23257264  0.25301429  1.21071226  1.29939237  3.92904462
##  [73]  4.07112121  3.78513073  2.83160983  1.41191959  0.28488816 -0.04006883
##  [79] -1.28812485 -0.74220308 -0.74424287 -0.32976863 -0.31752860 -0.98342470
##  [85] -2.04217397 -1.20184647 -1.31314616  0.45270778 -0.93468943 -0.20680752
##  [91] -0.29613748  0.15497575  0.22025744 -0.73310547  1.30806278  1.61203256
##  [97]  4.42693491  3.79591780  3.27848542  0.68061022 -0.62425847 -1.11211846
## [103]  0.04164014  0.59240357 -0.15810424  0.39101368 -1.92189820 -1.50741039
## [109] -2.59060462 -3.89098912 -2.51252738 -3.45825773 -2.26278511 -0.93523383
## [115]  0.07413764  0.83334886  1.28389670  1.34833602  3.06177019  2.98115137
## [121]  3.71727357  3.17046413  2.39423349  1.98646516  2.92352912  1.69753466
## [127]  2.18824295  2.31910758  1.98048956  1.12411345 -0.47375475 -1.38212484
## [133] -2.31108442 -2.26562282 -2.62211380 -2.26938378 -1.57393069 -0.56321701
## [139]  1.57589801  1.65267412  1.80012273  2.53204975  3.72627716  3.97712776
## [145]  3.44105725  0.58660225  1.46428641 -0.51695507 -0.57765858  1.69949100
## [151]  1.51248377  2.98314953 -0.81043866 -1.02122299 -1.37591544 -0.14779506
## [157]  1.31440815  3.22462748  4.38519006  3.98666624  4.07252161  2.61160764
## [163]  1.92537895 -1.70502573 -2.72222986 -3.24361938 -0.27688538  0.87342985
## [169]  2.50264542  1.00860632  1.15325179 -1.81437043 -0.92501023 -1.18146222
## [175] -0.02037563  0.94652009  1.17246770  2.08111275  3.60870710  4.52620181
## [181]  4.56792960  2.75523948  2.28308227  0.79090755  2.43630393  0.12650863
## [187]  0.38802680 -0.48922578 -0.39939179 -0.71118176 -1.07369267 -0.53512569
## [193]  0.48185240  1.52990415  3.93599432  4.75299655  5.28489601  3.75245965
## [199]  5.76106696  5.08023491  5.03046078  3.85049062  2.27094879  1.61300623
## [205]  0.02267186 -0.08744134 -0.23338993 -1.01395405 -4.02632785 -4.41061552
## [211] -5.02289664 -2.94041531 -2.16023161 -0.87458164 -1.76626866 -0.53794493
## [217] -0.27753067  0.71955739  2.19354067  2.33905070  2.84874980  2.50865574
## [223]  2.52684453  3.16087589  3.22420516  3.72442687  1.90727460  1.27139490
## [229]  1.66409882  0.23091397  1.10296539  0.37155340  1.69901525  1.20826458
## [235]  1.54849208 -0.89323198 -0.40844829 -1.97195019 -1.36977976 -2.76244287
## [241] -1.88853615 -1.38886217 -0.87915921  1.38576118  1.73484421  3.45643730
## [247]  4.90637915  3.88230417  4.70024354  4.04594276  3.83665310  3.63604751
## [253]  1.69745094  1.83280517  0.13589632  1.24990445 -0.25440835  0.60581161
## [259] -0.95359799 -0.74837042 -2.72398269 -2.15183291 -1.51561139 -0.53368698
## [265] -1.67162994 -2.15962923 -1.06604857  1.13495225  0.89677762  0.92454452
## [271]  0.14354987  0.49726828  0.03722489 -0.87570167 -1.33912012 -0.47863083
## [277] -0.18724669 -0.22304216 -0.89877996  0.52922646 -0.01897051  1.64938777
## [283]  2.32971329  2.98499263  2.59721428  1.95311423  0.73468623  1.76477012
## [289]  1.07548761  3.11749005  1.74249123  1.55297139  0.67230168  0.33991628
## [295] -0.10447830 -1.75292012 -1.80251894 -2.90523171 -0.99909951
#Yt-1
yt_1_arma <- arma22[-300]
yt_1_arma
##   [1] -2.75189059 -1.74814288 -2.98064692 -1.12111691 -1.75293106 -1.33898765
##   [7] -2.09046996 -3.56829323 -4.32225209 -6.49932813 -7.02769509 -6.95242810
##  [13] -6.26996407 -3.43890672 -3.74182891 -2.97181976 -3.49823015 -3.96328709
##  [19] -4.21591372 -4.99194225 -5.61517562 -5.49498965 -5.32810268 -6.08211738
##  [25] -5.70927763 -6.49640104 -6.19781946 -5.63181804 -4.16631811 -1.43386858
##  [31] -1.32659085  1.33518960 -0.57718012  1.13545868  2.56923465  2.89049818
##  [37]  2.80495292  1.68426168  2.77538382  1.29220743  3.17981524  3.04188012
##  [43]  3.84589813  3.47054592  2.25362466  1.27634579  1.31729358  3.02358708
##  [49]  2.83893413  1.81428668  0.10302896 -0.45121970 -0.85290753 -0.66635425
##  [55] -0.93510416 -2.14779642 -2.08562341 -1.51503473 -0.24121274  0.91556687
##  [61]  0.64537308  0.48311177 -1.14217407 -1.12039092 -1.27141453  0.91636167
##  [67]  2.04091439  2.13232979  2.23257264  0.25301429  1.21071226  1.29939237
##  [73]  3.92904462  4.07112121  3.78513073  2.83160983  1.41191959  0.28488816
##  [79] -0.04006883 -1.28812485 -0.74220308 -0.74424287 -0.32976863 -0.31752860
##  [85] -0.98342470 -2.04217397 -1.20184647 -1.31314616  0.45270778 -0.93468943
##  [91] -0.20680752 -0.29613748  0.15497575  0.22025744 -0.73310547  1.30806278
##  [97]  1.61203256  4.42693491  3.79591780  3.27848542  0.68061022 -0.62425847
## [103] -1.11211846  0.04164014  0.59240357 -0.15810424  0.39101368 -1.92189820
## [109] -1.50741039 -2.59060462 -3.89098912 -2.51252738 -3.45825773 -2.26278511
## [115] -0.93523383  0.07413764  0.83334886  1.28389670  1.34833602  3.06177019
## [121]  2.98115137  3.71727357  3.17046413  2.39423349  1.98646516  2.92352912
## [127]  1.69753466  2.18824295  2.31910758  1.98048956  1.12411345 -0.47375475
## [133] -1.38212484 -2.31108442 -2.26562282 -2.62211380 -2.26938378 -1.57393069
## [139] -0.56321701  1.57589801  1.65267412  1.80012273  2.53204975  3.72627716
## [145]  3.97712776  3.44105725  0.58660225  1.46428641 -0.51695507 -0.57765858
## [151]  1.69949100  1.51248377  2.98314953 -0.81043866 -1.02122299 -1.37591544
## [157] -0.14779506  1.31440815  3.22462748  4.38519006  3.98666624  4.07252161
## [163]  2.61160764  1.92537895 -1.70502573 -2.72222986 -3.24361938 -0.27688538
## [169]  0.87342985  2.50264542  1.00860632  1.15325179 -1.81437043 -0.92501023
## [175] -1.18146222 -0.02037563  0.94652009  1.17246770  2.08111275  3.60870710
## [181]  4.52620181  4.56792960  2.75523948  2.28308227  0.79090755  2.43630393
## [187]  0.12650863  0.38802680 -0.48922578 -0.39939179 -0.71118176 -1.07369267
## [193] -0.53512569  0.48185240  1.52990415  3.93599432  4.75299655  5.28489601
## [199]  3.75245965  5.76106696  5.08023491  5.03046078  3.85049062  2.27094879
## [205]  1.61300623  0.02267186 -0.08744134 -0.23338993 -1.01395405 -4.02632785
## [211] -4.41061552 -5.02289664 -2.94041531 -2.16023161 -0.87458164 -1.76626866
## [217] -0.53794493 -0.27753067  0.71955739  2.19354067  2.33905070  2.84874980
## [223]  2.50865574  2.52684453  3.16087589  3.22420516  3.72442687  1.90727460
## [229]  1.27139490  1.66409882  0.23091397  1.10296539  0.37155340  1.69901525
## [235]  1.20826458  1.54849208 -0.89323198 -0.40844829 -1.97195019 -1.36977976
## [241] -2.76244287 -1.88853615 -1.38886217 -0.87915921  1.38576118  1.73484421
## [247]  3.45643730  4.90637915  3.88230417  4.70024354  4.04594276  3.83665310
## [253]  3.63604751  1.69745094  1.83280517  0.13589632  1.24990445 -0.25440835
## [259]  0.60581161 -0.95359799 -0.74837042 -2.72398269 -2.15183291 -1.51561139
## [265] -0.53368698 -1.67162994 -2.15962923 -1.06604857  1.13495225  0.89677762
## [271]  0.92454452  0.14354987  0.49726828  0.03722489 -0.87570167 -1.33912012
## [277] -0.47863083 -0.18724669 -0.22304216 -0.89877996  0.52922646 -0.01897051
## [283]  1.64938777  2.32971329  2.98499263  2.59721428  1.95311423  0.73468623
## [289]  1.76477012  1.07548761  3.11749005  1.74249123  1.55297139  0.67230168
## [295]  0.33991628 -0.10447830 -1.75292012 -1.80251894 -2.90523171
plot(y=yt_arma,x=yt_1_arma)

Berdasarkan scatterplot tersebut, terlihat bahwa terdapat hubungan positif antara \(Y_t\) dengan \(Y_{t-1}\). Hal ini sesuai dengan teori yang ada

cor(yt_arma,yt_1_arma)
## [1] 0.8918177

Korelasi antara \(Y_t\) dengan \(Y_{t-2}\)

#Yt
yt_arma2 <- arma22[-c(1,2)]
yt_arma2
##   [1] -2.98064692 -1.12111691 -1.75293106 -1.33898765 -2.09046996 -3.56829323
##   [7] -4.32225209 -6.49932813 -7.02769509 -6.95242810 -6.26996407 -3.43890672
##  [13] -3.74182891 -2.97181976 -3.49823015 -3.96328709 -4.21591372 -4.99194225
##  [19] -5.61517562 -5.49498965 -5.32810268 -6.08211738 -5.70927763 -6.49640104
##  [25] -6.19781946 -5.63181804 -4.16631811 -1.43386858 -1.32659085  1.33518960
##  [31] -0.57718012  1.13545868  2.56923465  2.89049818  2.80495292  1.68426168
##  [37]  2.77538382  1.29220743  3.17981524  3.04188012  3.84589813  3.47054592
##  [43]  2.25362466  1.27634579  1.31729358  3.02358708  2.83893413  1.81428668
##  [49]  0.10302896 -0.45121970 -0.85290753 -0.66635425 -0.93510416 -2.14779642
##  [55] -2.08562341 -1.51503473 -0.24121274  0.91556687  0.64537308  0.48311177
##  [61] -1.14217407 -1.12039092 -1.27141453  0.91636167  2.04091439  2.13232979
##  [67]  2.23257264  0.25301429  1.21071226  1.29939237  3.92904462  4.07112121
##  [73]  3.78513073  2.83160983  1.41191959  0.28488816 -0.04006883 -1.28812485
##  [79] -0.74220308 -0.74424287 -0.32976863 -0.31752860 -0.98342470 -2.04217397
##  [85] -1.20184647 -1.31314616  0.45270778 -0.93468943 -0.20680752 -0.29613748
##  [91]  0.15497575  0.22025744 -0.73310547  1.30806278  1.61203256  4.42693491
##  [97]  3.79591780  3.27848542  0.68061022 -0.62425847 -1.11211846  0.04164014
## [103]  0.59240357 -0.15810424  0.39101368 -1.92189820 -1.50741039 -2.59060462
## [109] -3.89098912 -2.51252738 -3.45825773 -2.26278511 -0.93523383  0.07413764
## [115]  0.83334886  1.28389670  1.34833602  3.06177019  2.98115137  3.71727357
## [121]  3.17046413  2.39423349  1.98646516  2.92352912  1.69753466  2.18824295
## [127]  2.31910758  1.98048956  1.12411345 -0.47375475 -1.38212484 -2.31108442
## [133] -2.26562282 -2.62211380 -2.26938378 -1.57393069 -0.56321701  1.57589801
## [139]  1.65267412  1.80012273  2.53204975  3.72627716  3.97712776  3.44105725
## [145]  0.58660225  1.46428641 -0.51695507 -0.57765858  1.69949100  1.51248377
## [151]  2.98314953 -0.81043866 -1.02122299 -1.37591544 -0.14779506  1.31440815
## [157]  3.22462748  4.38519006  3.98666624  4.07252161  2.61160764  1.92537895
## [163] -1.70502573 -2.72222986 -3.24361938 -0.27688538  0.87342985  2.50264542
## [169]  1.00860632  1.15325179 -1.81437043 -0.92501023 -1.18146222 -0.02037563
## [175]  0.94652009  1.17246770  2.08111275  3.60870710  4.52620181  4.56792960
## [181]  2.75523948  2.28308227  0.79090755  2.43630393  0.12650863  0.38802680
## [187] -0.48922578 -0.39939179 -0.71118176 -1.07369267 -0.53512569  0.48185240
## [193]  1.52990415  3.93599432  4.75299655  5.28489601  3.75245965  5.76106696
## [199]  5.08023491  5.03046078  3.85049062  2.27094879  1.61300623  0.02267186
## [205] -0.08744134 -0.23338993 -1.01395405 -4.02632785 -4.41061552 -5.02289664
## [211] -2.94041531 -2.16023161 -0.87458164 -1.76626866 -0.53794493 -0.27753067
## [217]  0.71955739  2.19354067  2.33905070  2.84874980  2.50865574  2.52684453
## [223]  3.16087589  3.22420516  3.72442687  1.90727460  1.27139490  1.66409882
## [229]  0.23091397  1.10296539  0.37155340  1.69901525  1.20826458  1.54849208
## [235] -0.89323198 -0.40844829 -1.97195019 -1.36977976 -2.76244287 -1.88853615
## [241] -1.38886217 -0.87915921  1.38576118  1.73484421  3.45643730  4.90637915
## [247]  3.88230417  4.70024354  4.04594276  3.83665310  3.63604751  1.69745094
## [253]  1.83280517  0.13589632  1.24990445 -0.25440835  0.60581161 -0.95359799
## [259] -0.74837042 -2.72398269 -2.15183291 -1.51561139 -0.53368698 -1.67162994
## [265] -2.15962923 -1.06604857  1.13495225  0.89677762  0.92454452  0.14354987
## [271]  0.49726828  0.03722489 -0.87570167 -1.33912012 -0.47863083 -0.18724669
## [277] -0.22304216 -0.89877996  0.52922646 -0.01897051  1.64938777  2.32971329
## [283]  2.98499263  2.59721428  1.95311423  0.73468623  1.76477012  1.07548761
## [289]  3.11749005  1.74249123  1.55297139  0.67230168  0.33991628 -0.10447830
## [295] -1.75292012 -1.80251894 -2.90523171 -0.99909951
#Yt-2
yt_2_arma <- arma22[-c(299,300)]
yt_2_arma
##   [1] -2.75189059 -1.74814288 -2.98064692 -1.12111691 -1.75293106 -1.33898765
##   [7] -2.09046996 -3.56829323 -4.32225209 -6.49932813 -7.02769509 -6.95242810
##  [13] -6.26996407 -3.43890672 -3.74182891 -2.97181976 -3.49823015 -3.96328709
##  [19] -4.21591372 -4.99194225 -5.61517562 -5.49498965 -5.32810268 -6.08211738
##  [25] -5.70927763 -6.49640104 -6.19781946 -5.63181804 -4.16631811 -1.43386858
##  [31] -1.32659085  1.33518960 -0.57718012  1.13545868  2.56923465  2.89049818
##  [37]  2.80495292  1.68426168  2.77538382  1.29220743  3.17981524  3.04188012
##  [43]  3.84589813  3.47054592  2.25362466  1.27634579  1.31729358  3.02358708
##  [49]  2.83893413  1.81428668  0.10302896 -0.45121970 -0.85290753 -0.66635425
##  [55] -0.93510416 -2.14779642 -2.08562341 -1.51503473 -0.24121274  0.91556687
##  [61]  0.64537308  0.48311177 -1.14217407 -1.12039092 -1.27141453  0.91636167
##  [67]  2.04091439  2.13232979  2.23257264  0.25301429  1.21071226  1.29939237
##  [73]  3.92904462  4.07112121  3.78513073  2.83160983  1.41191959  0.28488816
##  [79] -0.04006883 -1.28812485 -0.74220308 -0.74424287 -0.32976863 -0.31752860
##  [85] -0.98342470 -2.04217397 -1.20184647 -1.31314616  0.45270778 -0.93468943
##  [91] -0.20680752 -0.29613748  0.15497575  0.22025744 -0.73310547  1.30806278
##  [97]  1.61203256  4.42693491  3.79591780  3.27848542  0.68061022 -0.62425847
## [103] -1.11211846  0.04164014  0.59240357 -0.15810424  0.39101368 -1.92189820
## [109] -1.50741039 -2.59060462 -3.89098912 -2.51252738 -3.45825773 -2.26278511
## [115] -0.93523383  0.07413764  0.83334886  1.28389670  1.34833602  3.06177019
## [121]  2.98115137  3.71727357  3.17046413  2.39423349  1.98646516  2.92352912
## [127]  1.69753466  2.18824295  2.31910758  1.98048956  1.12411345 -0.47375475
## [133] -1.38212484 -2.31108442 -2.26562282 -2.62211380 -2.26938378 -1.57393069
## [139] -0.56321701  1.57589801  1.65267412  1.80012273  2.53204975  3.72627716
## [145]  3.97712776  3.44105725  0.58660225  1.46428641 -0.51695507 -0.57765858
## [151]  1.69949100  1.51248377  2.98314953 -0.81043866 -1.02122299 -1.37591544
## [157] -0.14779506  1.31440815  3.22462748  4.38519006  3.98666624  4.07252161
## [163]  2.61160764  1.92537895 -1.70502573 -2.72222986 -3.24361938 -0.27688538
## [169]  0.87342985  2.50264542  1.00860632  1.15325179 -1.81437043 -0.92501023
## [175] -1.18146222 -0.02037563  0.94652009  1.17246770  2.08111275  3.60870710
## [181]  4.52620181  4.56792960  2.75523948  2.28308227  0.79090755  2.43630393
## [187]  0.12650863  0.38802680 -0.48922578 -0.39939179 -0.71118176 -1.07369267
## [193] -0.53512569  0.48185240  1.52990415  3.93599432  4.75299655  5.28489601
## [199]  3.75245965  5.76106696  5.08023491  5.03046078  3.85049062  2.27094879
## [205]  1.61300623  0.02267186 -0.08744134 -0.23338993 -1.01395405 -4.02632785
## [211] -4.41061552 -5.02289664 -2.94041531 -2.16023161 -0.87458164 -1.76626866
## [217] -0.53794493 -0.27753067  0.71955739  2.19354067  2.33905070  2.84874980
## [223]  2.50865574  2.52684453  3.16087589  3.22420516  3.72442687  1.90727460
## [229]  1.27139490  1.66409882  0.23091397  1.10296539  0.37155340  1.69901525
## [235]  1.20826458  1.54849208 -0.89323198 -0.40844829 -1.97195019 -1.36977976
## [241] -2.76244287 -1.88853615 -1.38886217 -0.87915921  1.38576118  1.73484421
## [247]  3.45643730  4.90637915  3.88230417  4.70024354  4.04594276  3.83665310
## [253]  3.63604751  1.69745094  1.83280517  0.13589632  1.24990445 -0.25440835
## [259]  0.60581161 -0.95359799 -0.74837042 -2.72398269 -2.15183291 -1.51561139
## [265] -0.53368698 -1.67162994 -2.15962923 -1.06604857  1.13495225  0.89677762
## [271]  0.92454452  0.14354987  0.49726828  0.03722489 -0.87570167 -1.33912012
## [277] -0.47863083 -0.18724669 -0.22304216 -0.89877996  0.52922646 -0.01897051
## [283]  1.64938777  2.32971329  2.98499263  2.59721428  1.95311423  0.73468623
## [289]  1.76477012  1.07548761  3.11749005  1.74249123  1.55297139  0.67230168
## [295]  0.33991628 -0.10447830 -1.75292012 -1.80251894
plot(y=yt_arma2,x=yt_2_arma)

Berdasarkan scatterplot tersebut, terlihat bahwa terdapat hubungan positif antara \(Y_t\) dengan \(Y_{t-2}\). Hal ini sesuai dengan teori yang ada

cor(yt_arma2,yt_2_arma)
## [1] 0.7836583

Korelasi antara \(Y_t\) dengan \(Y_{t-3}\)

#Yt
yt_arma3 <- arma22[-c(1,2,3)]
yt_arma3
##   [1] -1.12111691 -1.75293106 -1.33898765 -2.09046996 -3.56829323 -4.32225209
##   [7] -6.49932813 -7.02769509 -6.95242810 -6.26996407 -3.43890672 -3.74182891
##  [13] -2.97181976 -3.49823015 -3.96328709 -4.21591372 -4.99194225 -5.61517562
##  [19] -5.49498965 -5.32810268 -6.08211738 -5.70927763 -6.49640104 -6.19781946
##  [25] -5.63181804 -4.16631811 -1.43386858 -1.32659085  1.33518960 -0.57718012
##  [31]  1.13545868  2.56923465  2.89049818  2.80495292  1.68426168  2.77538382
##  [37]  1.29220743  3.17981524  3.04188012  3.84589813  3.47054592  2.25362466
##  [43]  1.27634579  1.31729358  3.02358708  2.83893413  1.81428668  0.10302896
##  [49] -0.45121970 -0.85290753 -0.66635425 -0.93510416 -2.14779642 -2.08562341
##  [55] -1.51503473 -0.24121274  0.91556687  0.64537308  0.48311177 -1.14217407
##  [61] -1.12039092 -1.27141453  0.91636167  2.04091439  2.13232979  2.23257264
##  [67]  0.25301429  1.21071226  1.29939237  3.92904462  4.07112121  3.78513073
##  [73]  2.83160983  1.41191959  0.28488816 -0.04006883 -1.28812485 -0.74220308
##  [79] -0.74424287 -0.32976863 -0.31752860 -0.98342470 -2.04217397 -1.20184647
##  [85] -1.31314616  0.45270778 -0.93468943 -0.20680752 -0.29613748  0.15497575
##  [91]  0.22025744 -0.73310547  1.30806278  1.61203256  4.42693491  3.79591780
##  [97]  3.27848542  0.68061022 -0.62425847 -1.11211846  0.04164014  0.59240357
## [103] -0.15810424  0.39101368 -1.92189820 -1.50741039 -2.59060462 -3.89098912
## [109] -2.51252738 -3.45825773 -2.26278511 -0.93523383  0.07413764  0.83334886
## [115]  1.28389670  1.34833602  3.06177019  2.98115137  3.71727357  3.17046413
## [121]  2.39423349  1.98646516  2.92352912  1.69753466  2.18824295  2.31910758
## [127]  1.98048956  1.12411345 -0.47375475 -1.38212484 -2.31108442 -2.26562282
## [133] -2.62211380 -2.26938378 -1.57393069 -0.56321701  1.57589801  1.65267412
## [139]  1.80012273  2.53204975  3.72627716  3.97712776  3.44105725  0.58660225
## [145]  1.46428641 -0.51695507 -0.57765858  1.69949100  1.51248377  2.98314953
## [151] -0.81043866 -1.02122299 -1.37591544 -0.14779506  1.31440815  3.22462748
## [157]  4.38519006  3.98666624  4.07252161  2.61160764  1.92537895 -1.70502573
## [163] -2.72222986 -3.24361938 -0.27688538  0.87342985  2.50264542  1.00860632
## [169]  1.15325179 -1.81437043 -0.92501023 -1.18146222 -0.02037563  0.94652009
## [175]  1.17246770  2.08111275  3.60870710  4.52620181  4.56792960  2.75523948
## [181]  2.28308227  0.79090755  2.43630393  0.12650863  0.38802680 -0.48922578
## [187] -0.39939179 -0.71118176 -1.07369267 -0.53512569  0.48185240  1.52990415
## [193]  3.93599432  4.75299655  5.28489601  3.75245965  5.76106696  5.08023491
## [199]  5.03046078  3.85049062  2.27094879  1.61300623  0.02267186 -0.08744134
## [205] -0.23338993 -1.01395405 -4.02632785 -4.41061552 -5.02289664 -2.94041531
## [211] -2.16023161 -0.87458164 -1.76626866 -0.53794493 -0.27753067  0.71955739
## [217]  2.19354067  2.33905070  2.84874980  2.50865574  2.52684453  3.16087589
## [223]  3.22420516  3.72442687  1.90727460  1.27139490  1.66409882  0.23091397
## [229]  1.10296539  0.37155340  1.69901525  1.20826458  1.54849208 -0.89323198
## [235] -0.40844829 -1.97195019 -1.36977976 -2.76244287 -1.88853615 -1.38886217
## [241] -0.87915921  1.38576118  1.73484421  3.45643730  4.90637915  3.88230417
## [247]  4.70024354  4.04594276  3.83665310  3.63604751  1.69745094  1.83280517
## [253]  0.13589632  1.24990445 -0.25440835  0.60581161 -0.95359799 -0.74837042
## [259] -2.72398269 -2.15183291 -1.51561139 -0.53368698 -1.67162994 -2.15962923
## [265] -1.06604857  1.13495225  0.89677762  0.92454452  0.14354987  0.49726828
## [271]  0.03722489 -0.87570167 -1.33912012 -0.47863083 -0.18724669 -0.22304216
## [277] -0.89877996  0.52922646 -0.01897051  1.64938777  2.32971329  2.98499263
## [283]  2.59721428  1.95311423  0.73468623  1.76477012  1.07548761  3.11749005
## [289]  1.74249123  1.55297139  0.67230168  0.33991628 -0.10447830 -1.75292012
## [295] -1.80251894 -2.90523171 -0.99909951
#Yt-3
yt_3_arma <- arma22[-c(298,299,300)]
yt_3_arma
##   [1] -2.75189059 -1.74814288 -2.98064692 -1.12111691 -1.75293106 -1.33898765
##   [7] -2.09046996 -3.56829323 -4.32225209 -6.49932813 -7.02769509 -6.95242810
##  [13] -6.26996407 -3.43890672 -3.74182891 -2.97181976 -3.49823015 -3.96328709
##  [19] -4.21591372 -4.99194225 -5.61517562 -5.49498965 -5.32810268 -6.08211738
##  [25] -5.70927763 -6.49640104 -6.19781946 -5.63181804 -4.16631811 -1.43386858
##  [31] -1.32659085  1.33518960 -0.57718012  1.13545868  2.56923465  2.89049818
##  [37]  2.80495292  1.68426168  2.77538382  1.29220743  3.17981524  3.04188012
##  [43]  3.84589813  3.47054592  2.25362466  1.27634579  1.31729358  3.02358708
##  [49]  2.83893413  1.81428668  0.10302896 -0.45121970 -0.85290753 -0.66635425
##  [55] -0.93510416 -2.14779642 -2.08562341 -1.51503473 -0.24121274  0.91556687
##  [61]  0.64537308  0.48311177 -1.14217407 -1.12039092 -1.27141453  0.91636167
##  [67]  2.04091439  2.13232979  2.23257264  0.25301429  1.21071226  1.29939237
##  [73]  3.92904462  4.07112121  3.78513073  2.83160983  1.41191959  0.28488816
##  [79] -0.04006883 -1.28812485 -0.74220308 -0.74424287 -0.32976863 -0.31752860
##  [85] -0.98342470 -2.04217397 -1.20184647 -1.31314616  0.45270778 -0.93468943
##  [91] -0.20680752 -0.29613748  0.15497575  0.22025744 -0.73310547  1.30806278
##  [97]  1.61203256  4.42693491  3.79591780  3.27848542  0.68061022 -0.62425847
## [103] -1.11211846  0.04164014  0.59240357 -0.15810424  0.39101368 -1.92189820
## [109] -1.50741039 -2.59060462 -3.89098912 -2.51252738 -3.45825773 -2.26278511
## [115] -0.93523383  0.07413764  0.83334886  1.28389670  1.34833602  3.06177019
## [121]  2.98115137  3.71727357  3.17046413  2.39423349  1.98646516  2.92352912
## [127]  1.69753466  2.18824295  2.31910758  1.98048956  1.12411345 -0.47375475
## [133] -1.38212484 -2.31108442 -2.26562282 -2.62211380 -2.26938378 -1.57393069
## [139] -0.56321701  1.57589801  1.65267412  1.80012273  2.53204975  3.72627716
## [145]  3.97712776  3.44105725  0.58660225  1.46428641 -0.51695507 -0.57765858
## [151]  1.69949100  1.51248377  2.98314953 -0.81043866 -1.02122299 -1.37591544
## [157] -0.14779506  1.31440815  3.22462748  4.38519006  3.98666624  4.07252161
## [163]  2.61160764  1.92537895 -1.70502573 -2.72222986 -3.24361938 -0.27688538
## [169]  0.87342985  2.50264542  1.00860632  1.15325179 -1.81437043 -0.92501023
## [175] -1.18146222 -0.02037563  0.94652009  1.17246770  2.08111275  3.60870710
## [181]  4.52620181  4.56792960  2.75523948  2.28308227  0.79090755  2.43630393
## [187]  0.12650863  0.38802680 -0.48922578 -0.39939179 -0.71118176 -1.07369267
## [193] -0.53512569  0.48185240  1.52990415  3.93599432  4.75299655  5.28489601
## [199]  3.75245965  5.76106696  5.08023491  5.03046078  3.85049062  2.27094879
## [205]  1.61300623  0.02267186 -0.08744134 -0.23338993 -1.01395405 -4.02632785
## [211] -4.41061552 -5.02289664 -2.94041531 -2.16023161 -0.87458164 -1.76626866
## [217] -0.53794493 -0.27753067  0.71955739  2.19354067  2.33905070  2.84874980
## [223]  2.50865574  2.52684453  3.16087589  3.22420516  3.72442687  1.90727460
## [229]  1.27139490  1.66409882  0.23091397  1.10296539  0.37155340  1.69901525
## [235]  1.20826458  1.54849208 -0.89323198 -0.40844829 -1.97195019 -1.36977976
## [241] -2.76244287 -1.88853615 -1.38886217 -0.87915921  1.38576118  1.73484421
## [247]  3.45643730  4.90637915  3.88230417  4.70024354  4.04594276  3.83665310
## [253]  3.63604751  1.69745094  1.83280517  0.13589632  1.24990445 -0.25440835
## [259]  0.60581161 -0.95359799 -0.74837042 -2.72398269 -2.15183291 -1.51561139
## [265] -0.53368698 -1.67162994 -2.15962923 -1.06604857  1.13495225  0.89677762
## [271]  0.92454452  0.14354987  0.49726828  0.03722489 -0.87570167 -1.33912012
## [277] -0.47863083 -0.18724669 -0.22304216 -0.89877996  0.52922646 -0.01897051
## [283]  1.64938777  2.32971329  2.98499263  2.59721428  1.95311423  0.73468623
## [289]  1.76477012  1.07548761  3.11749005  1.74249123  1.55297139  0.67230168
## [295]  0.33991628 -0.10447830 -1.75292012
plot(y=yt_arma3,x=yt_3_arma)

Berdasarkan scatterplot tersebut, terlihat bahwa terdapat hubungan positif antara \(Y_t\) dengan \(Y_{t-3}\). Hal ini sesuai dengan teori yang ada

cor(yt_arma3,yt_3_arma)
## [1] 0.6044325