Library

library(readxl)
library(tseries)
library(forecast)
library(TTR)
library(TSA)
library(graphics)
library(dplyr)
library(ggplot2)

Import Data

Data yang digunakan adalah data harga emas bulanan di United Kingdom (dalam USD) dari Bulan Januari tahun 1979 sampai Desember tahun 2020 yang merupakan data deret waktu.

data_emas <- read_excel("C:/Users/ASUS/Downloads/harga emas negara.xlsx")
View(data_emas)
data.emas <- data_emas %>%
  select(Time, UK)

data.table::data.table(data.emas)
##            Time     UK
##          <POSc>  <num>
##   1: 1979-01-01  117.4
##   2: 1979-02-01  124.2
##   3: 1979-03-01  116.2
##   4: 1979-04-01  118.8
##   5: 1979-05-01  132.7
##  ---                  
## 500: 2020-08-01 1461.9
## 501: 2020-09-01 1459.6
## 502: 2020-10-01 1455.4
## 503: 2020-11-01 1320.2
## 504: 2020-12-01 1380.9
emas.ts <- ts(data.emas$UK)
emas.ts.month <- ts(data.emas$UK, start = c(1979, 1), frequency = 12)

Plot Data

# Plot Data
data.emas$Time <- as.Date(data.emas$Time)
ggplot(data.emas, aes(x = Time, y = UK)) + geom_line()

Berdasarkan plot deret waktu diatas, terlihat bahwa data memiliki pola tidak stasioner.

Partisi Data

Data harga emas UK di partisi menjadi dua bagian yaitu data training (Januari 1979 - Juli 2012) dan data testing (Agustus 2012 - Desember 2020).

# Partisi Data
data.emas.training <- window(emas.ts, start = 1, end = 403)
data.emas.training 
## Time Series:
## Start = 1 
## End = 403 
## Frequency = 1 
##   [1]  117.4  124.2  116.2  118.8  132.7  127.3  131.9  139.9  180.4  184.0
##  [11]  189.0  230.6  288.1  280.3  228.5  229.4  228.4  277.3  262.2  263.4
##  [21]  279.3  258.2  262.8  246.7  214.0  221.8  228.9  225.5  231.5  220.7
##  [31]  220.5  229.9  237.5  229.6  212.0  208.2  205.7  199.1  179.6  201.4
##  [41]  181.7  182.1  197.3  239.7  234.3  252.4  268.6  282.5  328.6  269.6
##  [51]  279.6  275.1  272.7  271.9  277.5  277.3  270.5  255.4  276.3  263.5
##  [61]  266.7  264.5  269.3  268.7  277.3  275.0  261.8  266.1  278.3  273.1
##  [71]  274.6  266.0  271.1  266.4  266.1  258.6  244.1  242.6  232.5  239.2
##  [81]  231.2  225.6  218.5  226.1  248.1  233.7  231.8  222.9  233.1  226.3
##  [91]  239.5  258.5  292.5  285.3  271.7  262.2  264.6  262.5  262.3  273.0
## [101]  276.7  277.2  290.5  277.6  282.7  272.2  269.7  257.7  258.8  240.3
## [111]  242.0  238.9  247.8  255.6  255.4  254.0  234.6  233.2  228.4  226.8
## [121]  225.1  221.8  227.0  223.5  230.1  240.8  221.0  228.7  226.9  237.8
## [131]  260.1  247.2  247.1  241.2  223.7  224.3  216.5  201.9  200.2  204.9
## [141]  218.0  195.2  198.4  200.1  186.3  189.9  204.5  207.5  212.1  227.5
## [151]  215.3  206.7  202.5  205.1  207.5  188.8  197.8  201.0  196.9  189.6
## [161]  184.5  180.4  186.4  171.5  195.9  217.1  220.8  219.9  222.2  230.2
## [171]  224.4  225.8  241.8  253.4  270.5  249.8  237.7  248.6  249.9  264.8
## [181]  252.1  256.8  262.2  248.3  256.4  251.6  249.9  251.1  250.4  235.4
## [191]  244.8  245.0  236.2  238.2  240.7  242.2  241.9  243.3  239.6  246.8
## [201]  242.6  242.5  253.6  249.3  268.4  261.7  259.7  260.8  252.1  245.9
## [211]  247.5  247.3  242.4  233.1  221.0  215.8  215.6  219.8  212.0  209.6
## [221]  211.3  201.0  199.3  200.6  205.6  185.7  176.2  176.4  186.5  180.6
## [231]  179.8  185.8  180.1  177.6  176.6  163.3  172.9  174.5  178.5  173.0
## [241]  173.7  179.2  173.1  178.0  167.5  165.6  157.8  158.5  181.6  182.3
## [251]  182.9  180.1  174.8  186.0  173.5  175.8  182.1  190.3  184.8  190.4
## [261]  185.1  182.2  189.8  183.7  181.0  184.9  181.3  183.9  188.3  192.4
## [271]  186.6  188.2  199.4  191.7  193.2  190.0  199.8  209.9  211.7  211.5
## [281]  223.2  209.0  195.0  202.2  205.8  202.6  205.0  215.7  223.6  220.6
## [291]  211.8  210.7  220.6  209.7  220.7  237.5  233.5  227.6  231.6  232.5
## [301]  219.6  213.3  230.5  219.1  214.5  218.3  215.2  226.4  229.7  232.3
## [311]  237.2  226.9  223.8  226.1  226.2  228.1  227.4  243.9  243.7  240.9
## [321]  267.5  265.9  286.4  298.8  320.0  317.5  335.5  354.3  349.0  331.7
## [331]  338.8  327.8  320.8  316.6  328.8  322.9  332.3  338.9  337.4  338.5
## [341]  333.2  324.2  327.5  333.2  364.7  380.1  381.1  418.8  464.4  488.4
## [351]  469.7  439.8  448.2  467.4  463.4  456.7  496.2  452.3  530.8  604.9
## [361]  637.8  667.9  639.4  596.1  604.9  567.5  566.4  586.3  622.6  630.9
## [371]  716.4  673.4  673.1  728.0  735.4  770.4  831.1  831.5  746.4  810.7
## [381]  829.4  842.4  888.4  897.7  828.5  867.5  897.7  920.6  933.5  937.7
## [391]  992.1 1113.8 1039.9 1066.9 1110.1  985.1 1105.2 1108.0 1040.5 1016.9
## [401] 1012.3 1019.2 1035.2
data.emas.test <- subset(emas.ts, start = 404, end = 504)
data.emas.test
## Time Series:
## Start = 404 
## End = 504 
## Frequency = 1 
##   [1] 1037.9 1099.8 1067.0 1077.0 1019.7 1050.0 1046.5 1052.6  943.9  919.8
##  [11]  785.9  867.1  901.6  819.1  824.1  764.9  727.3  761.2  791.5  774.8
##  [21]  763.1  745.5  769.1  761.3  774.2  750.4  727.7  755.2  773.5  839.1
##  [31]  785.6  799.6  768.0  780.8  744.6  703.9  738.0  735.4  739.7  705.4
##  [41]  719.2  783.8  886.1  860.6  877.6  832.8  988.0 1010.8  999.7 1018.1
##  [51] 1041.9  942.9  927.4  964.0 1009.0  995.5  978.9  980.8  956.4  961.5
##  [61] 1018.0  956.4  956.5  945.7  954.4  945.9  956.5  943.7  953.4  981.0
##  [71]  947.1  930.8  925.1  910.4  950.9  954.3 1004.2 1005.9  991.8  994.1
##  [81]  983.6 1027.9 1107.1 1165.9 1255.0 1205.3 1167.7 1128.8 1143.4 1201.8
##  [91] 1260.4 1297.6 1349.9 1398.3 1431.0 1497.1 1461.9 1459.6 1455.4 1320.2
## [101] 1380.9

Plot Data Partisi

# Data Training
plot.ts(data.emas.training, main = "Data Training Harga Emas", xlab = "Bulan", ylab = "UK")

# Data Testing
plot.ts(data.emas.test, main = "Data Testing Harga Emas", xlab = "Bulan", ylab = "UK")

Stasioneritas Data

Plot ACF

# Stasioneritas Data
acf(data.emas.training, main = "Plot ACF Data Harga Emas UK")

Uji ADF

adf.test(data.emas.training)
## Warning in adf.test(data.emas.training): p-value greater than printed p-value
## 
##  Augmented Dickey-Fuller Test
## 
## data:  data.emas.training
## Dickey-Fuller = 1.5662, Lag order = 7, p-value = 0.99
## alternative hypothesis: stationary

Berdasarkan hasil uji ADF diperoleh p-value sebesar 0.99 > 0.05 yang berarti bahwa H0 diterima atau data tidak stasioner. Karena data tidak stasioner maka selanjutnya dilakukan differencing untuk membuat data stasioner sebelum dilakukan identifikasi model.

Differencing

# Differencing Ordo 1
data.emas.diff <- diff(data.emas.training, difference = 1)
plot.ts(data.emas.diff, lty = 1, xlab = "Waktu", ylab = "Data Harga Emas UK Differencing")
points(data.emas.diff)

acf(data.emas.diff, main = "Plot ACF Data Harga Emas UK Differencing", lag.max = 10)

adf.test(data.emas.diff)
## Warning in adf.test(data.emas.diff): p-value smaller than printed p-value
## 
##  Augmented Dickey-Fuller Test
## 
## data:  data.emas.diff
## Dickey-Fuller = -7.6743, Lag order = 7, p-value = 0.01
## alternative hypothesis: stationary

Berdasarkan hasil uji ADF, diperoleh nilai p-value sebesar 0.01 < 0.05 yang berarti H0 ditolak, sehingga data harga emas telah stasioner setelah dilakukan differencing ordo 1. Karena data telah stasioner selanjutnya akan dilakukan identifikasi model.

Identifikasi Model

Plot ACF

acf(data.emas.diff, main="Plot ACF Data Harga Emas UK", lag.max = 10) 

Plot PACF

pacf(data.emas.diff, main="Plot PACF Data Harga Emas UK", lag.max = 10) 

Plot EACF

eacf(data.emas.diff, ar.max = 10, ma.max = 10)
## AR/MA
##    0 1 2 3 4 5 6 7 8 9 10
## 0  x o x x o x x o o o x 
## 1  x o o x o x x o o o x 
## 2  x x o o o o o o o o x 
## 3  x x o o o o o o o o x 
## 4  x x x x o o o o o o x 
## 5  x x x o o o o o o o o 
## 6  x x o o o x o o o o o 
## 7  x x x o o x o o o o o 
## 8  x x o o x x o o o o o 
## 9  x x x x x o o o o o o 
## 10 x x x o x o x o o o o

Kandidat Model

Berdasarkan plot ACF (cut off setelah lag ke-1), PACF (cut off setelah lag ke-4), dan EACF, diperoleh kandidat model:

  1. ARIMA (4,1,1)

  2. ARIMA (4,1,0)

  3. ARIMA (1,1,1)

  4. ARIMA (1,1,0)

  5. ARIMA (2,1,1)

Pendugaan Parameter dan Penentuan Model Terbaik

# Uji Signifikansi Parameter
arima411 <- arima(data.emas.diff, order = c(4,1,1),include.mean = FALSE, method = "ML") 
arima411
## 
## Call:
## arima(x = data.emas.diff, order = c(4, 1, 1), include.mean = FALSE, method = "ML")
## 
## Coefficients:
##           ar1      ar2     ar3      ar4      ma1
##       -0.1341  -0.1478  0.1109  -0.1694  -0.9693
## s.e.   0.0501   0.0508  0.0507   0.0500   0.0123
## 
## sigma^2 estimated as 405.1:  log likelihood = -1774.61,  aic = 3559.22
arima410 <- arima(data.emas.diff, order = c(4,1,0),include.mean = FALSE, method = "ML") 
arima410
## 
## Call:
## arima(x = data.emas.diff, order = c(4, 1, 0), include.mean = FALSE, method = "ML")
## 
## Coefficients:
##           ar1      ar2      ar3      ar4
##       -0.8739  -0.7659  -0.3336  -0.2471
## s.e.   0.0485   0.0636   0.0637   0.0489
## 
## sigma^2 estimated as 500.2:  log likelihood = -1815.7,  aic = 3639.4
arima111 <- arima(data.emas.diff, order = c(1,1,1),include.mean = FALSE, method = "ML")
arima111
## 
## Call:
## arima(x = data.emas.diff, order = c(1, 1, 1), include.mean = FALSE, method = "ML")
## 
## Coefficients:
##           ar1      ma1
##       -0.1500  -0.9769
## s.e.   0.0499   0.0100
## 
## sigma^2 estimated as 434.9:  log likelihood = -1788.76,  aic = 3581.53
arima110 <- arima(data.emas.diff, order = c(1,1,0),include.mean = FALSE, method = "ML")
arima110
## 
## Call:
## arima(x = data.emas.diff, order = c(1, 1, 0), include.mean = FALSE, method = "ML")
## 
## Coefficients:
##           ar1
##       -0.5126
## s.e.   0.0428
## 
## sigma^2 estimated as 738:  log likelihood = -1893.25,  aic = 3788.5
arima211 <- arima(data.emas.diff, order = c(2,1,1),include.mean = FALSE, method = "ML") 
arima211
## 
## Call:
## arima(x = data.emas.diff, order = c(2, 1, 1), include.mean = FALSE, method = "ML")
## 
## Coefficients:
##           ar1      ar2      ma1
##       -0.1778  -0.1500  -0.9707
## s.e.   0.0502   0.0501   0.0116
## 
## sigma^2 estimated as 425.4:  log likelihood = -1784.35,  aic = 3574.71

AIC

# AIC
aic.arima <- data.frame(
  "Model" = c("ARIMA(4,1,1)", "ARIMA(4,1,0)", "ARIMA(1,1,1)", "ARIMA(1,1,0)", "ARIMA(2,1,1)"),
  "AIC" = c(arima411$aic, arima410$aic, arima111$aic, arima110$aic, arima211$aic)
)
aic.arima
##          Model      AIC
## 1 ARIMA(4,1,1) 3559.218
## 2 ARIMA(4,1,0) 3639.398
## 3 ARIMA(1,1,1) 3581.526
## 4 ARIMA(1,1,0) 3788.498
## 5 ARIMA(2,1,1) 3574.706

Berdasarkan hasil di atas dapat disimpulkan bahwa ARIMA (4,1,1) merupakan model terbaik karena model tersebut memiliki nilai AIC terkecil yaitu 3559.218.

Diagnostik Model

# Residuals
arima.411<-arima(data.emas.training,  order=c(4,1,1), include.mean = FALSE, method="ML")
residual.arima <- arima.411$residuals

Uji Non-Autokorelasi

# Uji Non-Autokorelasi
Box.test(residual.arima, type = "Ljung-Box")
## 
##  Box-Ljung test
## 
## data:  residual.arima
## X-squared = 0.070551, df = 1, p-value = 0.7905

Berdasarkan hasil uji Ljung-Box di atas dapat disimpulkan bahwa H0 tidak ditolak karena p-value sebesar 0.7905 > 0.05 yang berarti tidak terdapat autokorelasi pada residuals dari model ARIMA

Uji Normalitas

# Uji Normalitas
shapiro.test(residual.arima)
## 
##  Shapiro-Wilk normality test
## 
## data:  residual.arima
## W = 0.84748, p-value < 2.2e-16
hist(residual.arima, main = "Histogram Residual", xlab = "Residual", breaks = 20)

qqnorm(residual.arima)
qqline(residual.arima, col = "red")

Berdasarkan hasil uji Shapiro-Wilk di atas dapat disimpulkan bahwa H0 ditolak karena p-value = 2.2e-16 < 0.05 sehingga sisaan dari model ARIMA tidak berdistribusi Normal.

Ukuran Keakuratan Ramalan Model Arima (4,1,1)

# Ukuran Keakuratan
dugaan <- fitted(arima411)
cbind(data.emas.training, dugaan)
## Time Series:
## Start = 1 
## End = 403 
## Frequency = 1 
##     data.emas.training       dugaan
##   1              117.4           NA
##   2              124.2   6.79320001
##   3              116.2   1.42794490
##   4              118.8   0.37263602
##   5              132.7   3.57387873
##   6              127.3  -0.92663116
##   7              131.9   3.14208300
##   8              139.9   4.57322774
##   9              180.4   1.53569416
##  10              184.0   4.55333060
##  11              189.0   3.37951058
##  12              230.6  12.94832238
##  13              288.1   2.12992616
##  14              280.3   4.14396088
##  15              228.5  11.92110883
##  16              229.4  18.99886777
##  17              228.4   7.34380120
##  18              277.3   6.40073427
##  19              262.2  14.85475394
##  20              263.4   5.42847481
##  21              279.3  18.32743065
##  22              258.2  -1.97153792
##  23              262.8  12.53960931
##  24              246.7  12.76777912
##  25              214.0   3.57778088
##  26              221.8  16.42734491
##  27              228.9   6.46119477
##  28              225.5   2.21487855
##  29              231.5  10.77907427
##  30              220.7   3.84757417
##  31              220.5   3.09671504
##  32              229.9   6.87334634
##  33              237.5   0.69375354
##  34              229.6   3.72718420
##  35              212.0   4.81840376
##  36              208.2   5.74974374
##  37              205.7   3.55922677
##  38              199.1   2.64961519
##  39              179.6   5.77162681
##  40              201.4   5.10667723
##  41              181.7   1.29982087
##  42              182.1  -0.67955181
##  43              197.3   9.57648757
##  44              239.7  -6.66590022
##  45              234.3  -1.62268251
##  46              252.4  -1.07806783
##  47              268.6   3.99964221
##  48              282.5  -8.68566820
##  49              328.6   3.42307237
##  50              269.6  -3.45875208
##  51              279.6   4.15720502
##  52              275.1  14.55771587
##  53              272.7 -11.40784440
##  54              271.9  16.18008124
##  55              277.5   1.81825397
##  56              277.3   3.52938457
##  57              270.5   3.05363293
##  58              255.4   4.90161948
##  59              276.3   4.64493451
##  60              263.5   1.79494243
##  61              266.7   0.73319485
##  62              264.5   9.03613126
##  63              269.3  -2.78931379
##  64              268.7   4.78898248
##  65              277.3   1.00481904
##  66              275.0   2.49524019
##  67              261.8   0.65442423
##  68              266.1   5.22941107
##  69              278.3   1.70214147
##  70              273.1  -0.98076830
##  71              274.6   3.84053043
##  72              266.0   3.34697886
##  73              271.1   0.07358276
##  74              266.4   3.57331344
##  75              266.1   0.35045692
##  76              258.6   4.41552382
##  77              244.1   0.94872617
##  78              242.6   4.61999955
##  79              232.5   2.17444058
##  80              239.2   1.47170143
##  81              231.2   3.27661003
##  82              225.6  -0.74093876
##  83              218.5   4.27782830
##  84              226.1  -0.70217849
##  85              248.1   0.56517921
##  86              233.7  -3.45231578
##  87              231.8   0.84745538
##  88              222.9   3.57073510
##  89              233.1  -4.19723040
##  90              226.3   2.27196748
##  91              239.5  -1.44292043
##  92              258.5   2.14479203
##  93              292.5  -6.18731249
##  94              285.3  -2.72131053
##  95              271.7  -2.29740975
##  96              262.2   4.98193959
##  97              264.6  -2.17813215
##  98              262.5   2.03130013
##  99              262.3   2.28796042
## 100              273.0   3.24751317
## 101              276.7  -0.78105920
## 102              277.2  -0.34234732
## 103              290.5   2.03493940
## 104              277.6  -1.48646113
## 105              282.7   0.61606337
## 106              272.2   4.17325242
## 107              269.7  -1.92035306
## 108              257.7   5.72942360
## 109              258.8   0.49666028
## 110              240.3   3.69207437
## 111              242.0   1.29400346
## 112              238.9   4.55665559
## 113              247.8  -2.41321870
## 114              255.6   2.59570201
## 115              255.4  -2.82544387
## 116              254.0   0.63472726
## 117              234.6  -0.24013201
## 118              233.2   1.06215202
## 119              228.4   2.45522346
## 120              226.8  -1.76484755
## 121              225.1   3.35973883
## 122              221.8  -0.68197665
## 123              227.0   0.39813321
## 124              223.5  -0.91128555
## 125              230.1  -1.24064023
## 126              240.8   0.14525233
## 127              221.0  -3.97886780
## 128              228.7   1.61441842
## 129              226.9   1.36436334
## 130              237.8  -5.60040948
## 131              260.1   2.82468089
## 132              247.2  -5.69691026
## 133              247.1   0.13599397
## 134              241.2   2.72709499
## 135              223.7  -4.48728628
## 136              224.3   4.91014906
## 137              216.5   1.25297592
## 138              201.9  -0.87723584
## 139              200.2   4.82822335
## 140              204.9  -0.09531504
## 141              218.0  -2.04394346
## 142              195.2  -1.06904480
## 143              198.4   0.36157961
## 144              200.1   2.11501091
## 145              186.3  -6.94428361
## 146              189.9   4.11220726
## 147              204.5  -0.51768337
## 148              207.5  -5.56583380
## 149              212.1  -0.81714144
## 150              227.5  -0.87921971
## 151              215.3  -5.21521390
## 152              206.7  -1.18143956
## 153              202.5   3.11415851
## 154              205.1  -3.12333881
## 155              207.5   0.56562064
## 156              188.8  -0.47827760
## 157              197.8   1.83085493
## 158              201.0   0.28012835
## 159              196.9  -5.25281625
## 160              189.6   3.26604509
## 161              184.5  -0.88653070
## 162              180.4  -0.66478634
## 163              186.4  -0.34742162
## 164              171.5  -0.86885124
## 165              195.9  -0.25083455
## 166              217.1  -0.72554246
## 167              220.8  -9.46176819
## 168              219.9   1.66164280
## 169              222.2  -2.22729873
## 170              230.2  -3.23657726
## 171              224.4  -1.67449941
## 172              225.8   0.34153188
## 173              241.8   1.53802352
## 174              253.4  -3.53694620
## 175              270.5  -1.50376767
## 176              249.8  -0.62120263
## 177              237.7   0.05763659
## 178              248.6   5.47368846
## 179              249.9  -3.83978360
## 180              264.8   1.56441268
## 181              252.1   2.66221379
## 182              256.8  -1.07928828
## 183              262.2   3.97859903
## 184              248.3  -4.00882935
## 185              256.4   4.77890642
## 186              251.6   1.91236645
## 187              249.9  -2.07421192
## 188              251.1   5.13825357
## 189              250.4  -0.98788592
## 190              235.4   1.37665741
## 191              244.8   2.86942433
## 192              245.0   1.20888334
## 193              236.2  -2.45860559
## 194              238.2   5.04279750
## 195              240.7  -0.32326251
## 196              242.2  -1.33935958
## 197              241.9   1.53068267
## 198              243.3   0.08930973
## 199              239.6  -0.02808331
## 200              246.8   0.26179825
## 201              242.6   0.26008318
## 202              242.5  -0.81253434
## 203              253.6   2.41740913
## 204              249.3  -2.53553106
## 205              268.4   0.20656941
## 206              261.7   0.47142353
## 207              259.7  -3.35268728
## 208              260.8   5.07623433
## 209              252.1  -2.98236507
## 210              245.9   2.59105572
## 211              247.5   2.98212472
## 212              247.3  -0.08794771
## 213              242.4   0.93494974
## 214              233.1   2.09390812
## 215              221.0   1.50801436
## 216              215.8   1.90023725
## 217              215.6   1.47935556
## 218              219.8   0.17252245
## 219              212.0   0.20671409
## 220              209.6   0.30565542
## 221              211.3   0.91291323
## 222              201.0  -2.48734207
## 223              199.3   0.90854055
## 224              200.6   0.98859779
## 225              205.6  -2.70083567
## 226              185.7  -0.41721698
## 227              176.2   0.65337846
## 228              176.4   2.52951992
## 229              186.5  -3.76843252
## 230              180.6  -0.73202700
## 231              179.8  -0.89421169
## 232              185.8   0.24399039
## 233              180.1  -4.69719520
## 234              177.6  -0.88732917
## 235              176.6   0.25338198
## 236              163.3  -2.90898828
## 237              172.9   0.53749012
## 238              174.5  -0.81357137
## 239              178.5  -4.66960087
## 240              173.0   1.08068808
## 241              173.7  -2.96914186
## 242              179.2  -0.66238928
## 243              173.1  -3.49378587
## 244              178.0  -0.43021595
## 245              167.5  -0.54562023
## 246              165.6  -2.51125240
## 247              157.8   1.81569859
## 248              158.5  -2.53078931
## 249              181.6   0.86350798
## 250              182.3  -4.82637570
## 251              182.9  -3.02114813
## 252              180.1   1.45815853
## 253              174.8  -4.48146362
## 254              186.0   0.11540566
## 255              173.5  -1.74811893
## 256              175.8  -1.03933067
## 257              182.1   2.83469540
## 258              190.3  -5.20712981
## 259              184.8   0.01508233
## 260              190.4  -0.66155928
## 261              185.1  -0.40035252
## 262              182.2  -2.57081048
## 263              189.8   2.26057927
## 264              183.7  -2.42817551
## 265              181.0  -0.14235035
## 266              184.9   2.10600616
## 267              181.3  -2.52514613
## 268              183.9   0.17058424
## 269              188.3   0.67804308
## 270              192.4  -2.31565963
## 271              186.6  -0.38632542
## 272              188.2  -0.03119273
## 273              199.4   0.15135242
## 274              191.7  -2.93817041
## 275              193.2   0.52972528
## 276              190.0   1.92998605
## 277              199.8  -2.67956034
## 278              209.9   0.87706161
## 279              211.7  -2.88177774
## 280              211.5   0.56871680
## 281              223.2  -0.12932232
## 282              209.0  -2.03828958
## 283              195.0   0.48782661
## 284              202.2   5.50338326
## 285              205.8  -2.20609147
## 286              202.6  -0.26800606
## 287              205.0   3.40355845
## 288              215.7  -0.36447512
## 289              223.6  -2.11018597
## 290              220.6  -0.88118791
## 291              211.8   0.90115950
## 292              210.7   1.27559771
## 293              220.6   0.29280569
## 294              209.7  -0.82225365
## 295              220.7   1.86913549
## 296              237.5   2.20175307
## 297              233.5  -5.53590592
## 298              227.6   2.39657889
## 299              231.6   2.40380483
## 300              232.5  -1.88380908
## 301              219.6   0.46758820
## 302              213.3   3.78648750
## 303              230.5   2.61046232
## 304              219.1  -2.07444930
## 305              214.5   1.07205665
## 306              218.3   5.70135748
## 307              215.2  -3.64224050
## 308              226.4   1.65824707
## 309              229.7   0.83243811
## 310              232.3  -2.33447711
## 311              237.2   1.83342442
## 312              226.9  -1.57665507
## 313              223.8   1.11520722
## 314              226.1   2.64058053
## 315              226.2  -1.23372873
## 316              228.1   1.67808085
## 317              227.4   1.14766400
## 318              243.9   0.01470253
## 319              243.7  -0.82975815
## 320              240.9  -1.70632023
## 321              267.5   3.42521603
## 322              265.9  -4.18912521
## 323              286.4  -2.13198263
## 324              298.8   3.46743158
## 325              320.0  -6.54780518
## 326              317.5   1.54921386
## 327              335.5  -1.34015147
## 328              354.3   2.35486868
## 329              349.0  -4.39763624
## 330              331.7   4.97766996
## 331              338.8   6.08101513
## 332              327.8   1.80506148
## 333              320.8   2.98593242
## 334              316.6   9.55791027
## 335              328.8   2.02769242
## 336              322.9   3.23687075
## 337              332.3   2.59301998
## 338              338.9   4.76958809
## 339              337.4  -1.84629289
## 340              338.5   4.42811769
## 341              333.2   2.27163923
## 342              324.2   2.08948885
## 343              327.5   4.85231861
## 344              333.2   2.55170583
## 345              364.7   1.18252294
## 346              380.1   0.28867150
## 347              381.1  -2.71982793
## 348              418.8   4.15973865
## 349              464.4  -3.76236173
## 350              488.4  -7.60157808
## 351              469.7   1.60683149
## 352              439.8   4.56076973
## 353              448.2   7.58260354
## 354              467.4   3.05048893
## 355              463.4   2.42941735
## 356              456.7   9.89300388
## 357              496.2   7.88370830
## 358              452.3  -1.34653748
## 359              530.8   5.33629581
## 360              604.9   9.07297939
## 361              637.8 -23.51112915
## 362              667.9  12.10052414
## 363              639.4  -2.10968679
## 364              596.1   1.52925370
## 365              604.9  17.47022592
## 366              567.5   6.37975272
## 367              566.4  11.82023362
## 368              586.3  21.67043811
## 369              622.6  -0.51662642
## 370              630.9   7.16327944
## 371              716.4   4.70800470
## 372              673.4  -0.76850486
## 373              673.1  -2.12501865
## 374              728.0  24.50286173
## 375              735.4 -15.61117634
## 376              770.4   9.81433086
## 377              831.1  12.79315419
## 378              831.5  -7.88467723
## 379              746.4   7.76681273
## 380              810.7  23.47132367
## 381              829.4   6.28184059
## 382              842.4  -8.56894314
## 383              888.4  30.65332391
## 384              897.7  -2.83015296
## 385              828.5   4.68013391
## 386              867.5  22.99196188
## 387              897.7  10.91268474
## 388              920.6  -5.79563809
## 389              933.5  22.66520774
## 390              937.7   5.47699640
## 391              992.1   8.76380482
## 392             1113.8   4.84458202
## 393             1039.9  -7.28750164
## 394             1066.9  13.99622474
## 395             1110.1  28.73121671
## 396              985.1 -21.00770746
## 397             1105.2  40.29814806
## 398             1108.0  19.43600705
## 399             1040.5 -22.96846712
## 400             1016.9  58.11358488
## 401             1012.3   5.57250176
## 402             1019.2   8.30174214
## 403             1035.2  20.68882071

Plot Dugaan

# Plot Dugaan
plot.ts(data.emas.training, xlab="Month", ylab="Data")
points(data.emas.training)
par(col="black")
lines(dugaan)

Forecast

# Forecast
ramalan.arima411<- forecast::forecast(data.emas.training, model = arima.411, h = 101)
ramalan.arima411
##     Point Forecast     Lo 80    Hi 80    Lo 95    Hi 95
## 404       1034.423 1008.1852 1060.661 994.2957 1074.550
## 405       1034.805  999.1098 1070.500 980.2140 1089.396
## 406       1036.957  994.8760 1079.038 972.5998 1101.314
## 407       1034.890  984.6673 1085.113 958.0809 1111.699
## 408       1035.228  979.6452 1090.811 950.2213 1120.235
## 409       1035.687  975.1851 1096.188 943.1575 1128.216
## 410       1035.009  969.4412 1100.576 934.7319 1135.285
## 411       1035.348  965.5610 1105.134 928.6181 1142.077
## 412       1035.392  961.4679 1109.316 922.3348 1148.450
## 413       1035.193  957.2679 1113.118 916.0169 1154.368
## 414       1035.349  953.7568 1116.941 910.5646 1160.133
## 415       1035.313  950.1327 1120.494 905.0409 1165.585
## 416       1035.267  946.6465 1123.888 899.7335 1170.801
## 417       1035.325  943.4264 1127.223 894.7783 1175.871
## 418       1035.297  940.2042 1130.390 889.8650 1180.729
## 419       1035.293  937.1184 1133.467 885.1481 1185.437
## 420       1035.310  934.1545 1136.466 880.6059 1190.015
## 421       1035.297  931.2358 1139.358 876.1491 1194.445
## 422       1035.300  928.4172 1142.183 871.8369 1198.763
## 423       1035.304  925.6725 1144.935 867.6371 1202.971
## 424       1035.299  922.9836 1147.615 863.5273 1207.071
## 425       1035.301  920.3666 1150.236 859.5238 1211.079
## 426       1035.302  917.8056 1152.798 855.6069 1214.997
## 427       1035.300  915.2968 1155.304 851.7707 1218.830
## 428       1035.301  912.8426 1157.760 848.0168 1222.586
## 429       1035.301  910.4350 1160.167 844.3349 1226.267
## 430       1035.301  908.0728 1162.529 840.7224 1229.879
## 431       1035.301  905.7546 1164.848 837.1768 1233.426
## 432       1035.301  903.4765 1167.126 833.6928 1236.909
## 433       1035.301  901.2372 1169.365 830.2681 1240.334
## 434       1035.301  899.0349 1171.567 826.8999 1243.702
## 435       1035.301  896.8674 1173.735 823.5850 1247.017
## 436       1035.301  894.7334 1175.869 820.3214 1250.281
## 437       1035.301  892.6314 1177.971 817.1066 1253.496
## 438       1035.301  890.5598 1180.042 813.9384 1256.664
## 439       1035.301  888.5175 1182.085 810.8150 1259.787
## 440       1035.301  886.5032 1184.099 807.7344 1262.868
## 441       1035.301  884.5158 1186.086 804.6949 1265.907
## 442       1035.301  882.5543 1188.048 801.6951 1268.907
## 443       1035.301  880.6176 1189.984 798.7332 1271.869
## 444       1035.301  878.7049 1191.897 795.8080 1274.794
## 445       1035.301  876.8153 1193.787 792.9181 1277.684
## 446       1035.301  874.9480 1195.654 790.0622 1280.540
## 447       1035.301  873.1021 1197.500 787.2392 1283.363
## 448       1035.301  871.2770 1199.325 784.4479 1286.154
## 449       1035.301  869.4720 1201.130 781.6874 1288.915
## 450       1035.301  867.6865 1202.916 778.9567 1291.645
## 451       1035.301  865.9197 1204.682 776.2546 1294.347
## 452       1035.301  864.1712 1206.431 773.5805 1297.022
## 453       1035.301  862.4404 1208.162 770.9335 1299.669
## 454       1035.301  860.7267 1209.875 768.3127 1302.289
## 455       1035.301  859.0297 1211.572 765.7173 1304.885
## 456       1035.301  857.3489 1213.253 763.1467 1307.455
## 457       1035.301  855.6838 1214.918 760.6002 1310.002
## 458       1035.301  854.0340 1216.568 758.0771 1312.525
## 459       1035.301  852.3991 1218.203 755.5767 1315.025
## 460       1035.301  850.7787 1219.823 753.0984 1317.504
## 461       1035.301  849.1724 1221.430 750.6418 1319.960
## 462       1035.301  847.5798 1223.022 748.2061 1322.396
## 463       1035.301  846.0006 1224.601 745.7910 1324.811
## 464       1035.301  844.4345 1226.168 743.3958 1327.206
## 465       1035.301  842.8811 1227.721 741.0201 1329.582
## 466       1035.301  841.3402 1229.262 738.6635 1331.939
## 467       1035.301  839.8114 1230.791 736.3254 1334.277
## 468       1035.301  838.2945 1232.308 734.0055 1336.597
## 469       1035.301  836.7891 1233.813 731.7033 1338.899
## 470       1035.301  835.2951 1235.307 729.4184 1341.184
## 471       1035.301  833.8122 1236.790 727.1505 1343.452
## 472       1035.301  832.3401 1238.262 724.8991 1345.703
## 473       1035.301  830.8787 1239.723 722.6640 1347.938
## 474       1035.301  829.4275 1241.175 720.4447 1350.157
## 475       1035.301  827.9866 1242.615 718.2409 1352.361
## 476       1035.301  826.5556 1244.047 716.0524 1354.550
## 477       1035.301  825.1343 1245.468 713.8788 1356.723
## 478       1035.301  823.7226 1246.879 711.7197 1358.882
## 479       1035.301  822.3202 1248.282 709.5750 1361.027
## 480       1035.301  820.9270 1249.675 707.4443 1363.158
## 481       1035.301  819.5429 1251.059 705.3274 1365.275
## 482       1035.301  818.1675 1252.435 703.2239 1367.378
## 483       1035.301  816.8008 1253.801 701.1337 1369.468
## 484       1035.301  815.4426 1255.160 699.0565 1371.546
## 485       1035.301  814.0927 1256.509 696.9921 1373.610
## 486       1035.301  812.7510 1257.851 694.9401 1375.662
## 487       1035.301  811.4173 1259.185 692.9005 1377.702
## 488       1035.301  810.0916 1260.510 690.8729 1379.729
## 489       1035.301  808.7736 1261.828 688.8572 1381.745
## 490       1035.301  807.4632 1263.139 686.8532 1383.749
## 491       1035.301  806.1604 1264.442 684.8606 1385.741
## 492       1035.301  804.8649 1265.737 682.8793 1387.723
## 493       1035.301  803.5766 1267.025 680.9091 1389.693
## 494       1035.301  802.2954 1268.307 678.9497 1391.652
## 495       1035.301  801.0213 1269.581 677.0011 1393.601
## 496       1035.301  799.7541 1270.848 675.0630 1395.539
## 497       1035.301  798.4936 1272.108 673.1353 1397.467
## 498       1035.301  797.2398 1273.362 671.2178 1399.384
## 499       1035.301  795.9926 1274.609 669.3104 1401.292
## 500       1035.301  794.7518 1275.850 667.4128 1403.189
## 501       1035.301  793.5175 1277.085 665.5250 1405.077
## 502       1035.301  792.2893 1278.313 663.6467 1406.955
## 503       1035.301  791.0674 1279.535 661.7779 1408.824
## 504       1035.301  789.8515 1280.751 659.9184 1410.684
plot(ramalan.arima411)

gabungan <- cbind(data.emas.test, ramalan.arima411)
df.gabungan <- as.data.frame(gabungan, digits=3)
df.gabungan %>%
  rename(
    "Data Aktual Harga Emas UK" = data.emas.test,
    Ramalan ="ramalan.arima411.Point Forecast",
    "Lo 80"="ramalan.arima411.Lo 80",
    "Hi 80"="ramalan.arima411.Hi 80",
    "Lo 95"="ramalan.arima411.Lo 95",
    "Hi 95"="ramalan.arima411.Hi 95"
  )
##     Data Aktual Harga Emas UK  Ramalan     Lo 80    Hi 80    Lo 95    Hi 95
## 1                      1037.9 1034.423 1008.1852 1060.661 994.2957 1074.550
## 2                      1099.8 1034.805  999.1098 1070.500 980.2140 1089.396
## 3                      1067.0 1036.957  994.8760 1079.038 972.5998 1101.314
## 4                      1077.0 1034.890  984.6673 1085.113 958.0809 1111.699
## 5                      1019.7 1035.228  979.6452 1090.811 950.2213 1120.235
## 6                      1050.0 1035.687  975.1851 1096.188 943.1575 1128.216
## 7                      1046.5 1035.009  969.4412 1100.576 934.7319 1135.285
## 8                      1052.6 1035.348  965.5610 1105.134 928.6181 1142.077
## 9                       943.9 1035.392  961.4679 1109.316 922.3348 1148.450
## 10                      919.8 1035.193  957.2679 1113.118 916.0169 1154.368
## 11                      785.9 1035.349  953.7568 1116.941 910.5646 1160.133
## 12                      867.1 1035.313  950.1327 1120.494 905.0409 1165.585
## 13                      901.6 1035.267  946.6465 1123.888 899.7335 1170.801
## 14                      819.1 1035.325  943.4264 1127.223 894.7783 1175.871
## 15                      824.1 1035.297  940.2042 1130.390 889.8650 1180.729
## 16                      764.9 1035.293  937.1184 1133.467 885.1481 1185.437
## 17                      727.3 1035.310  934.1545 1136.466 880.6059 1190.015
## 18                      761.2 1035.297  931.2358 1139.358 876.1491 1194.445
## 19                      791.5 1035.300  928.4172 1142.183 871.8369 1198.763
## 20                      774.8 1035.304  925.6725 1144.935 867.6371 1202.971
## 21                      763.1 1035.299  922.9836 1147.615 863.5273 1207.071
## 22                      745.5 1035.301  920.3666 1150.236 859.5238 1211.079
## 23                      769.1 1035.302  917.8056 1152.798 855.6069 1214.997
## 24                      761.3 1035.300  915.2968 1155.304 851.7707 1218.830
## 25                      774.2 1035.301  912.8426 1157.760 848.0168 1222.586
## 26                      750.4 1035.301  910.4350 1160.167 844.3349 1226.267
## 27                      727.7 1035.301  908.0728 1162.529 840.7224 1229.879
## 28                      755.2 1035.301  905.7546 1164.848 837.1768 1233.426
## 29                      773.5 1035.301  903.4765 1167.126 833.6928 1236.909
## 30                      839.1 1035.301  901.2372 1169.365 830.2681 1240.334
## 31                      785.6 1035.301  899.0349 1171.567 826.8999 1243.702
## 32                      799.6 1035.301  896.8674 1173.735 823.5850 1247.017
## 33                      768.0 1035.301  894.7334 1175.869 820.3214 1250.281
## 34                      780.8 1035.301  892.6314 1177.971 817.1066 1253.496
## 35                      744.6 1035.301  890.5598 1180.042 813.9384 1256.664
## 36                      703.9 1035.301  888.5175 1182.085 810.8150 1259.787
## 37                      738.0 1035.301  886.5032 1184.099 807.7344 1262.868
## 38                      735.4 1035.301  884.5158 1186.086 804.6949 1265.907
## 39                      739.7 1035.301  882.5543 1188.048 801.6951 1268.907
## 40                      705.4 1035.301  880.6176 1189.984 798.7332 1271.869
## 41                      719.2 1035.301  878.7049 1191.897 795.8080 1274.794
## 42                      783.8 1035.301  876.8153 1193.787 792.9181 1277.684
## 43                      886.1 1035.301  874.9480 1195.654 790.0622 1280.540
## 44                      860.6 1035.301  873.1021 1197.500 787.2392 1283.363
## 45                      877.6 1035.301  871.2770 1199.325 784.4479 1286.154
## 46                      832.8 1035.301  869.4720 1201.130 781.6874 1288.915
## 47                      988.0 1035.301  867.6865 1202.916 778.9567 1291.645
## 48                     1010.8 1035.301  865.9197 1204.682 776.2546 1294.347
## 49                      999.7 1035.301  864.1712 1206.431 773.5805 1297.022
## 50                     1018.1 1035.301  862.4404 1208.162 770.9335 1299.669
## 51                     1041.9 1035.301  860.7267 1209.875 768.3127 1302.289
## 52                      942.9 1035.301  859.0297 1211.572 765.7173 1304.885
## 53                      927.4 1035.301  857.3489 1213.253 763.1467 1307.455
## 54                      964.0 1035.301  855.6838 1214.918 760.6002 1310.002
## 55                     1009.0 1035.301  854.0340 1216.568 758.0771 1312.525
## 56                      995.5 1035.301  852.3991 1218.203 755.5767 1315.025
## 57                      978.9 1035.301  850.7787 1219.823 753.0984 1317.504
## 58                      980.8 1035.301  849.1724 1221.430 750.6418 1319.960
## 59                      956.4 1035.301  847.5798 1223.022 748.2061 1322.396
## 60                      961.5 1035.301  846.0006 1224.601 745.7910 1324.811
## 61                     1018.0 1035.301  844.4345 1226.168 743.3958 1327.206
## 62                      956.4 1035.301  842.8811 1227.721 741.0201 1329.582
## 63                      956.5 1035.301  841.3402 1229.262 738.6635 1331.939
## 64                      945.7 1035.301  839.8114 1230.791 736.3254 1334.277
## 65                      954.4 1035.301  838.2945 1232.308 734.0055 1336.597
## 66                      945.9 1035.301  836.7891 1233.813 731.7033 1338.899
## 67                      956.5 1035.301  835.2951 1235.307 729.4184 1341.184
## 68                      943.7 1035.301  833.8122 1236.790 727.1505 1343.452
## 69                      953.4 1035.301  832.3401 1238.262 724.8991 1345.703
## 70                      981.0 1035.301  830.8787 1239.723 722.6640 1347.938
## 71                      947.1 1035.301  829.4275 1241.175 720.4447 1350.157
## 72                      930.8 1035.301  827.9866 1242.615 718.2409 1352.361
## 73                      925.1 1035.301  826.5556 1244.047 716.0524 1354.550
## 74                      910.4 1035.301  825.1343 1245.468 713.8788 1356.723
## 75                      950.9 1035.301  823.7226 1246.879 711.7197 1358.882
## 76                      954.3 1035.301  822.3202 1248.282 709.5750 1361.027
## 77                     1004.2 1035.301  820.9270 1249.675 707.4443 1363.158
## 78                     1005.9 1035.301  819.5429 1251.059 705.3274 1365.275
## 79                      991.8 1035.301  818.1675 1252.435 703.2239 1367.378
## 80                      994.1 1035.301  816.8008 1253.801 701.1337 1369.468
## 81                      983.6 1035.301  815.4426 1255.160 699.0565 1371.546
## 82                     1027.9 1035.301  814.0927 1256.509 696.9921 1373.610
## 83                     1107.1 1035.301  812.7510 1257.851 694.9401 1375.662
## 84                     1165.9 1035.301  811.4173 1259.185 692.9005 1377.702
## 85                     1255.0 1035.301  810.0916 1260.510 690.8729 1379.729
## 86                     1205.3 1035.301  808.7736 1261.828 688.8572 1381.745
## 87                     1167.7 1035.301  807.4632 1263.139 686.8532 1383.749
## 88                     1128.8 1035.301  806.1604 1264.442 684.8606 1385.741
## 89                     1143.4 1035.301  804.8649 1265.737 682.8793 1387.723
## 90                     1201.8 1035.301  803.5766 1267.025 680.9091 1389.693
## 91                     1260.4 1035.301  802.2954 1268.307 678.9497 1391.652
## 92                     1297.6 1035.301  801.0213 1269.581 677.0011 1393.601
## 93                     1349.9 1035.301  799.7541 1270.848 675.0630 1395.539
## 94                     1398.3 1035.301  798.4936 1272.108 673.1353 1397.467
## 95                     1431.0 1035.301  797.2398 1273.362 671.2178 1399.384
## 96                     1497.1 1035.301  795.9926 1274.609 669.3104 1401.292
## 97                     1461.9 1035.301  794.7518 1275.850 667.4128 1403.189
## 98                     1459.6 1035.301  793.5175 1277.085 665.5250 1405.077
## 99                     1455.4 1035.301  792.2893 1278.313 663.6467 1406.955
## 100                    1320.2 1035.301  791.0674 1279.535 661.7779 1408.824
## 101                    1380.9 1035.301  789.8515 1280.751 659.9184 1410.684

Akurasi

# Akurasi
accuracy(ramalan.arima411, data.emas.test)
##                      ME     RMSE       MAE         MPE      MAPE      MASE
## Training set   2.449186  20.4481  12.44926   0.4258411  3.915648  0.998604
## Test set     -63.501670 204.8856 166.60784 -10.4824622 18.195143 13.364265
##                     ACF1 Theil's U
## Training set -0.01318205        NA
## Test set      0.94906751  4.641143

Intepretasi Nilai MAPE

##   Nilai MAPE                    Interpretasi
## 1       <10% Kemampuan peramalan sangat baik
## 2    10%-20%        Kemampuan peramalan baik
## 3    20%-50%       Kemampuan peramalan layak
## 4       >50%       Kemampuan peramalan buruk

Berdasarkan hasil di atas diperoleh nilai MAPE pada data testing sebesar 18.2% yang berarti model ARIMA (4,1,1) memiliki kemampuan peramalan baik.

Peramalan Harga Emas United Kingdom

# Ramalan Harga Emas UK 12 Bulan ke Depan
ramalan_arima411 <- forecast::forecast(emas.ts,model = arima.411, h = 12)
plot(ramalan_arima411)