#MEMANGGIL DATA#  
data=read.table(file.choose(),header=TRUE)  
data 
##      Y  X1   X2   X3
## 1 57.5  78 2.75 29.5
## 2 52.8  69 2.15 26.3
## 3 61.3  77 4.41 32.2
## 4 67.0  88 5.52 36.5
## 5 53.5  67 3.21 27.2
## 6 62.7  80 4.32 27.7
## 7 56.2  74 2.31 28.3
## 8 68.5  94 4.30 30.3
## 9 69.2 102 3.71 28.7
# MEMANGGIL LIBRARY #
library(ggplot2)

# a. Scatter Plot X1 dan Y
ggplot(data, aes(x = X1, y = Y)) +
  geom_point(size = 1.5, alpha = 0.5) +
  geom_smooth(method = "lm", se = FALSE,
              color = "red", linewidth = 1) +
  labs(
    title = "Scatter Plot X1 vs Y",
    x = "X1",
    y = "Y"
  ) +
  theme_gray()
## `geom_smooth()` using formula = 'y ~ x'

# b. Scatter Plot X2 dan Y
ggplot(data, aes(x = X2, y = Y)) +
  geom_point(size = 1.5, alpha = 0.5) +
  geom_smooth(method = "lm", se = FALSE,
              color = "blue", linewidth = 1) +
  labs(
    title = "Scatter Plot X2 vs Y",
    x = "X2",
    y = "Y"
  ) +
  theme_gray()
## `geom_smooth()` using formula = 'y ~ x'

# c. Scatter Plot X3 dan Y
ggplot(data, aes(x = X3, y = Y)) +
  geom_point(size = 1.5, alpha = 0.5) +
  geom_smooth(method = "lm", se = FALSE,
              color = "red", linewidth = 1) +
  labs(
    title = "Scatter Plot X3 vs Y",
    x = "X3",
    y = "Y"
  ) +
  theme_gray()
## `geom_smooth()` using formula = 'y ~ x'

summary(data)
##        Y               X1            X2              X3       
##  Min.   :52.80   Min.   : 67   Min.   :2.150   Min.   :26.30  
##  1st Qu.:56.20   1st Qu.: 74   1st Qu.:2.750   1st Qu.:27.70  
##  Median :61.30   Median : 78   Median :3.710   Median :28.70  
##  Mean   :60.97   Mean   : 81   Mean   :3.631   Mean   :29.63  
##  3rd Qu.:67.00   3rd Qu.: 88   3rd Qu.:4.320   3rd Qu.:30.30  
##  Max.   :69.20   Max.   :102   Max.   :5.520   Max.   :36.50
#Library yang digunakan
library(stats)
library(car)
## Loading required package: carData
library(lmtest)
## Loading required package: zoo
## 
## Attaching package: 'zoo'
## The following objects are masked from 'package:base':
## 
##     as.Date, as.Date.numeric
library(nortest)
library(zoo)

#Regresi Y-X1
a1 = lm(formula = Y ~ X1, data = data)
bptest(a1)
## 
##  studentized Breusch-Pagan test
## 
## data:  a1
## BP = 1.715, df = 1, p-value = 0.1903
a1resid = (resid(a1))
a1resid
##          1          2          3          4          5          6          7 
## -1.9127561 -1.9510242  2.4052142  2.4075419 -0.2150838  2.2513035 -1.1408752 
##          8          9 
##  0.7997207 -2.6440410
a1resid = abs(resid(a1))
a1resid
##         1         2         3         4         5         6         7         8 
## 1.9127561 1.9510242 2.4052142 2.4075419 0.2150838 2.2513035 1.1408752 0.7997207 
##         9 
## 2.6440410
a12 = lm(formula = a1resid ~ X1, data = data)
summary(a12)
## 
## Call:
## lm(formula = a1resid ~ X1, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -1.3200 -0.4062  0.2952  0.5324  0.7722 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)
## (Intercept) -0.57193    2.04979  -0.279    0.788
## X1           0.02864    0.02508   1.142    0.291
## 
## Residual standard error: 0.8219 on 7 degrees of freedom
## Multiple R-squared:  0.157,  Adjusted R-squared:  0.03657 
## F-statistic: 1.304 on 1 and 7 DF,  p-value: 0.2911
dwtest(a1)
## 
##  Durbin-Watson test
## 
## data:  a1
## DW = 1.785, p-value = 0.2872
## alternative hypothesis: true autocorrelation is greater than 0
bgtest(a1)
## 
##  Breusch-Godfrey test for serial correlation of order up to 1
## 
## data:  a1
## LM test = 0.033549, df = 1, p-value = 0.8547
shapiro.test(resid(a1))
## 
##  Shapiro-Wilk normality test
## 
## data:  resid(a1)
## W = 0.87986, p-value = 0.1565
summary(a1)
## 
## Call:
## lm(formula = Y ~ X1, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -2.6440 -1.9128 -0.2151  2.2513  2.4075 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 19.01108    5.42272   3.506 0.009915 ** 
## X1           0.51797    0.06635   7.807 0.000106 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.174 on 7 degrees of freedom
## Multiple R-squared:  0.897,  Adjusted R-squared:  0.8823 
## F-statistic: 60.95 on 1 and 7 DF,  p-value: 0.0001065
#Regresi Y-X2
a2 = lm(formula = Y ~ X2, data = data)
bptest(a2)
## 
##  studentized Breusch-Pagan test
## 
## data:  a2
## BP = 0.072359, df = 1, p-value = 0.7879
a2resid = (resid(a2))
a2resid
##          1          2          3          4          5          6          7 
##  0.3353100 -1.7757020 -3.0275565 -2.1171842 -5.6495807 -1.2392084  0.9339012 
##          8          9 
##  4.6470912  7.8929294
a2resid = abs(resid(a2))
a2resid
##         1         2         3         4         5         6         7         8 
## 0.3353100 1.7757020 3.0275565 2.1171842 5.6495807 1.2392084 0.9339012 4.6470912 
##         9 
## 7.8929294
a22 = lm(formula = a2resid ~ X2, data = data)
summary(a22)
## 
## Call:
## lm(formula = a2resid ~ X2, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -2.3452 -1.7837 -0.6405  1.2837  4.7895 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)
## (Intercept)   1.4690     3.1460   0.467    0.655
## X2            0.4406     0.8321   0.529    0.613
## 
## Residual standard error: 2.631 on 7 degrees of freedom
## Multiple R-squared:  0.03851,    Adjusted R-squared:  -0.09885 
## F-statistic: 0.2804 on 1 and 7 DF,  p-value: 0.6128
dwtest(a2)
## 
##  Durbin-Watson test
## 
## data:  a2
## DW = 0.50193, p-value = 0.002713
## alternative hypothesis: true autocorrelation is greater than 0
bgtest(a2)
## 
##  Breusch-Godfrey test for serial correlation of order up to 1
## 
## data:  a2
## LM test = 5.4817, df = 1, p-value = 0.01922
shapiro.test(resid(a2))
## 
##  Shapiro-Wilk normality test
## 
## data:  resid(a2)
## W = 0.93927, p-value = 0.5742
summary(a2)
## 
## Call:
## lm(formula = Y ~ X2, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -5.6496 -2.1172 -1.2392  0.9339  7.8929 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)   45.298      5.254   8.621 5.64e-05 ***
## X2             4.315      1.390   3.105   0.0172 *  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 4.394 on 7 degrees of freedom
## Multiple R-squared:  0.5793, Adjusted R-squared:  0.5192 
## F-statistic:  9.64 on 1 and 7 DF,  p-value: 0.0172
#Regresi Y-X3
a3 = lm(formula = Y ~ X3, data = data)
bptest(a3)
## 
##  studentized Breusch-Pagan test
## 
## data:  a3
## BP = 0.62733, df = 1, p-value = 0.4283
a3resid = (resid(a3))
a3resid
##         1         2         3         4         5         6         7         8 
## -3.314678 -4.366959 -2.592442 -1.794065 -4.692880  3.937164 -3.246783  6.773392 
##         9 
##  9.297252
a3resid = abs(resid(a3))
a3resid
##        1        2        3        4        5        6        7        8 
## 3.314678 4.366959 2.592442 1.794065 4.692880 3.937164 3.246783 6.773392 
##        9 
## 9.297252
a32 = lm(formula = a3resid ~ X3, data = data)
summary(a32)
## 
## Call:
## lm(formula = a3resid ~ X3, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -1.6039 -1.0955 -1.0751 -0.4915  4.5679 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)
## (Intercept)  13.4360     7.5924    1.77    0.120
## X3           -0.3034     0.2550   -1.19    0.273
## 
## Residual standard error: 2.246 on 7 degrees of freedom
## Multiple R-squared:  0.1682, Adjusted R-squared:  0.0494 
## F-statistic: 1.416 on 1 and 7 DF,  p-value: 0.2729
dwtest(a3)
## 
##  Durbin-Watson test
## 
## data:  a3
## DW = 1.117, p-value = 0.08255
## alternative hypothesis: true autocorrelation is greater than 0
bgtest(a3)
## 
##  Breusch-Godfrey test for serial correlation of order up to 1
## 
## data:  a3
## LM test = 0.80317, df = 1, p-value = 0.3701
shapiro.test(resid(a3))
## 
##  Shapiro-Wilk normality test
## 
## data:  resid(a3)
## W = 0.81761, p-value = 0.03238
summary(a3)
## 
## Call:
## lm(formula = Y ~ X3, data = data)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -4.693 -3.315 -2.592  3.937  9.297 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)
## (Intercept)  27.1873    18.9650   1.434    0.195
## X3            1.1399     0.6369   1.790    0.117
## 
## Residual standard error: 5.611 on 7 degrees of freedom
## Multiple R-squared:  0.314,  Adjusted R-squared:  0.216 
## F-statistic: 3.204 on 1 and 7 DF,  p-value: 0.1166
#Regresi Y ~ X1+X2+X3
a4 = lm(formula = Y ~ X1 + X2 + X3, data = data)
vif(a4)
##       X1       X2       X3 
## 1.403219 3.093549 2.607991
bptest(a4)
## 
##  studentized Breusch-Pagan test
## 
## data:  a4
## BP = 0.52402, df = 3, p-value = 0.9136
a4resid = (resid(a4))
a4resid
##          1          2          3          4          5          6          7 
## -0.2980857 -0.2141744  0.4714083 -0.4745650 -0.9524106  0.4760829  0.9274363 
##          8          9 
##  0.7466056 -0.6822975
a4resid = abs(resid(a4))
a4resid
##         1         2         3         4         5         6         7         8 
## 0.2980857 0.2141744 0.4714083 0.4745650 0.9524106 0.4760829 0.9274363 0.7466056 
##         9 
## 0.6822975
a42 = lm(formula = a4resid ~ X1 + X2 + X3, data = data)
summary(a42)
## 
## Call:
## lm(formula = a4resid ~ X1 + X2 + X3, data = data)
## 
## Residuals:
##        1        2        3        4        5        6        7        8 
## -0.24968 -0.37078 -0.06495 -0.01987  0.35744 -0.17650  0.37477  0.12608 
##        9 
##  0.02347 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)
## (Intercept)  1.000238   1.548904   0.646    0.547
## X1           0.002391   0.011660   0.205    0.846
## X2           0.035130   0.179452   0.196    0.853
## X3          -0.024936   0.059127  -0.422    0.691
## 
## Residual standard error: 0.3226 on 5 degrees of freedom
## Multiple R-squared:  0.04467,    Adjusted R-squared:  -0.5285 
## F-statistic: 0.07793 on 3 and 5 DF,  p-value: 0.9692
dwtest(a4)
## 
##  Durbin-Watson test
## 
## data:  a4
## DW = 1.6446, p-value = 0.1165
## alternative hypothesis: true autocorrelation is greater than 0
bgtest(a4)
## 
##  Breusch-Godfrey test for serial correlation of order up to 1
## 
## data:  a4
## LM test = 0.51249, df = 1, p-value = 0.4741
shapiro.test(resid(a4))
## 
##  Shapiro-Wilk normality test
## 
## data:  resid(a4)
## W = 0.93208, p-value = 0.5014
summary(a4)
## 
## Call:
## lm(formula = Y ~ X1 + X2 + X3, data = data)
## 
## Residuals:
##       1       2       3       4       5       6       7       8       9 
## -0.2981 -0.2142  0.4714 -0.4746 -0.9524  0.4761  0.9274  0.7466 -0.6823 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 21.87353    4.07389   5.369  0.00302 ** 
## X1           0.41277    0.03067  13.460 4.05e-05 ***
## X2           2.20267    0.47199   4.667  0.00550 ** 
## X3          -0.07895    0.15551  -0.508  0.63330    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.8484 on 5 degrees of freedom
## Multiple R-squared:  0.9888, Adjusted R-squared:  0.9821 
## F-statistic: 147.1 on 3 and 5 DF,  p-value: 2.696e-05