\(~\)

(a) Use general-to-specific to come to a model. Start by regressing the federal funds rate on the other 7 variables and eliminate 1 variable at a time.

\(~\)

data <- read.table("./Week 3 - Test.txt", header = TRUE)
reg <- lm(INTRATE ~ INFL + PROD + UNEMPL + COMMPRI + PCE + PERSINC + HOUST, data = data)
summary (reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PROD + UNEMPL + COMMPRI + PCE + 
##     PERSINC + HOUST, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -7.4066 -1.4340 -0.1175  1.3555  7.7386 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -0.221161   0.244995  -0.903   0.3670    
## INFL         0.696059   0.062229  11.185  < 2e-16 ***
## PROD        -0.057743   0.039900  -1.447   0.1483    
## UNEMPL       0.102481   0.096757   1.059   0.2899    
## COMMPRI     -0.005521   0.002974  -1.857   0.0638 .  
## PCE          0.344380   0.069455   4.958 9.08e-07 ***
## PERSINC      0.246999   0.060590   4.077 5.13e-05 ***
## HOUST       -0.019411   0.004672  -4.155 3.68e-05 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.188 on 652 degrees of freedom
## Multiple R-squared:  0.6385, Adjusted R-squared:  0.6346 
## F-statistic: 164.5 on 7 and 652 DF,  p-value: < 2.2e-16

\(~\)

With a t-value of 1.059, the first removed variable is ‘unemployment rate’.

\(~\)

reg <- lm(INTRATE ~ INFL + PROD + COMMPRI + PCE + PERSINC + HOUST, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PROD + COMMPRI + PCE + PERSINC + 
##     HOUST, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -7.5322 -1.4982 -0.1005  1.3882  7.6954 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -0.290851   0.236016  -1.232   0.2183    
## INFL         0.693309   0.062180  11.150  < 2e-16 ***
## PROD        -0.025460   0.025752  -0.989   0.3232    
## COMMPRI     -0.006514   0.002822  -2.308   0.0213 *  
## PCE          0.368561   0.065602   5.618 2.86e-08 ***
## PERSINC      0.251581   0.060441   4.162 3.57e-05 ***
## HOUST       -0.021023   0.004417  -4.760 2.39e-06 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.188 on 653 degrees of freedom
## Multiple R-squared:  0.6379, Adjusted R-squared:  0.6346 
## F-statistic: 191.7 on 6 and 653 DF,  p-value: < 2.2e-16

\(~\)

The next removed variable is ‘production’, with a -0.989 t-value.

\(~\)

reg <- lm(INTRATE ~ INFL + COMMPRI + PCE + PERSINC + HOUST, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + COMMPRI + PCE + PERSINC + HOUST, 
##     data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -7.1631 -1.5244 -0.1125  1.3715  7.6725 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -0.240119   0.230366  -1.042  0.29764    
## INFL         0.717527   0.057152  12.555  < 2e-16 ***
## COMMPRI     -0.007501   0.002640  -2.841  0.00464 ** 
## PCE          0.340525   0.059156   5.756 1.32e-08 ***
## PERSINC      0.240242   0.059342   4.048 5.77e-05 ***
## HOUST       -0.020530   0.004389  -4.678 3.52e-06 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.188 on 654 degrees of freedom
## Multiple R-squared:  0.6374, Adjusted R-squared:  0.6346 
## F-statistic: 229.9 on 5 and 654 DF,  p-value: < 2.2e-16

\(~\)

Now all variables can be considered significant, since their t-values are all above 2 and their standard error close to 0. The final version of the model thus includes the variables:

\(~\)

(b) Use specific-to-general to come to a model. Start by regressing the federal funds rate on only a constant and add 1 variable at a time. Is the model the same as in (a)?

\(~\)

First we regress the federal funds rate on each constant, to define which variable will be added first.

\(~\)

reg <- lm(INTRATE ~ INFL, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -5.9947 -1.5592  0.0603  1.4990  8.2910 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  1.64209    0.15863   10.35   <2e-16 ***
## INFL         0.94534    0.03268   28.93   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.403 on 658 degrees of freedom
## Multiple R-squared:  0.5598, Adjusted R-squared:  0.5591 
## F-statistic: 836.6 on 1 and 658 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ PROD, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ PROD, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -5.4733 -2.3293 -0.1199  1.8050 13.7859 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  5.39419    0.16551  32.592   <2e-16 ***
## PROD        -0.01592    0.02966  -0.537    0.592    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 3.621 on 658 degrees of freedom
## Multiple R-squared:  0.0004375,  Adjusted R-squared:  -0.001082 
## F-statistic: 0.288 on 1 and 658 DF,  p-value: 0.5917
reg <- lm(INTRATE ~ UNEMPL, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ UNEMPL, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -5.4502 -2.3216 -0.4573  1.9157 14.4183 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  4.54462    0.18496  24.571  < 2e-16 ***
## UNEMPL       0.45247    0.07018   6.447 2.21e-10 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 3.513 on 658 degrees of freedom
## Multiple R-squared:  0.05942,    Adjusted R-squared:  0.05799 
## F-statistic: 41.57 on 1 and 658 DF,  p-value: 2.206e-10
reg <- lm(INTRATE ~ COMMPRI, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ COMMPRI, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -6.0892 -2.4343 -0.2646  1.9122 13.8328 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  5.401743   0.141559   38.16  < 2e-16 ***
## COMMPRI     -0.011526   0.004191   -2.75  0.00613 ** 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 3.601 on 658 degrees of freedom
## Multiple R-squared:  0.01136,    Adjusted R-squared:  0.009859 
## F-statistic: 7.562 on 1 and 658 DF,  p-value: 0.006125
reg <- lm(INTRATE ~ PCE, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ PCE, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -6.0034 -2.2094 -0.1965  1.6315 10.9790 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -0.33613    0.28161  -1.194    0.233    
## PCE          0.82938    0.03799  21.832   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.758 on 658 degrees of freedom
## Multiple R-squared:  0.4201, Adjusted R-squared:  0.4192 
## F-statistic: 476.6 on 1 and 658 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ PERSINC, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ PERSINC, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -5.6152 -2.2902 -0.2105  1.7326 13.9662 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  5.12454    0.20844  24.586   <2e-16 ***
## PERSINC      0.10429    0.07186   1.451    0.147    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 3.616 on 658 degrees of freedom
## Multiple R-squared:  0.003191,   Adjusted R-squared:  0.001676 
## F-statistic: 2.106 on 1 and 658 DF,  p-value: 0.1472
reg <- lm(INTRATE ~ HOUST, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ HOUST, data = data)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -6.950 -2.223 -0.156  1.833 14.152 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  5.403640   0.138710  38.956  < 2e-16 ***
## HOUST       -0.030950   0.006062  -5.106 4.32e-07 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 3.552 on 658 degrees of freedom
## Multiple R-squared:  0.03811,    Adjusted R-squared:  0.03665 
## F-statistic: 26.07 on 1 and 658 DF,  p-value: 4.317e-07

\(~\)

With the highest F-statistic, ‘Inflation’ is the first variable added to the model. We now repeat the process for all the remaining ones.

\(~\)

reg <- lm(INTRATE ~ INFL + PROD, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PROD, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -5.1592 -1.6762  0.0141  1.3730  7.9203 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  1.24890    0.17619   7.088 3.51e-12 ***
## INFL         0.97498    0.03273  29.785  < 2e-16 ***
## PROD         0.09472    0.01971   4.805 1.92e-06 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.364 on 657 degrees of freedom
## Multiple R-squared:  0.5747, Adjusted R-squared:  0.5734 
## F-statistic: 443.9 on 2 and 657 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + UNEMPL, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + UNEMPL, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -5.1135 -1.7040 -0.0674  1.2620  8.4818 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  1.12297    0.16879   6.653 6.05e-11 ***
## INFL         0.92573    0.03159  29.300  < 2e-16 ***
## UNEMPL       0.33581    0.04642   7.235 1.30e-12 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.315 on 657 degrees of freedom
## Multiple R-squared:  0.5922, Adjusted R-squared:  0.591 
## F-statistic: 477.1 on 2 and 657 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + COMMPRI, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + COMMPRI, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -6.2351 -1.5814  0.0128  1.4972  8.3501 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  1.682029   0.160251  10.496   <2e-16 ***
## INFL         0.940702   0.032760  28.715   <2e-16 ***
## COMMPRI     -0.004637   0.002803  -1.654   0.0986 .  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.4 on 657 degrees of freedom
## Multiple R-squared:  0.5616, Adjusted R-squared:  0.5602 
## F-statistic: 420.8 on 2 and 657 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + PCE, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PCE, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -5.8640 -1.7141 -0.0637  1.5733  7.8959 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  0.10125    0.23417   0.432    0.666    
## INFL         0.71575    0.04094  17.483   <2e-16 ***
## PCE          0.35616    0.04146   8.590   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.28 on 657 degrees of freedom
## Multiple R-squared:  0.6042, Adjusted R-squared:  0.603 
## F-statistic: 501.5 on 2 and 657 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + PERSINC, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -7.4839 -1.4786 -0.1279  1.4757  7.8344 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  0.44720    0.19510   2.292   0.0222 *  
## INFL         1.01224    0.03148  32.156   <2e-16 ***
## PERSINC      0.43597    0.04600   9.478   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.256 on 657 degrees of freedom
## Multiple R-squared:  0.6127, Adjusted R-squared:  0.6115 
## F-statistic: 519.7 on 2 and 657 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + HOUST, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + HOUST, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -6.1362 -1.5837  0.1037  1.4405  8.2763 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  1.676666   0.163125  10.278   <2e-16 ***
## INFL         0.938290   0.033590  27.934   <2e-16 ***
## HOUST       -0.003841   0.004215  -0.911    0.362    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.404 on 657 degrees of freedom
## Multiple R-squared:  0.5603, Adjusted R-squared:  0.559 
## F-statistic: 418.6 on 2 and 657 DF,  p-value: < 2.2e-16

\(~\)

The highest f-statistic now belongs to ‘Personal income’, which is the second added variable.

\(~\)

reg <- lm(INTRATE ~ INFL + PERSINC + PROD, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + PROD, data = data)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -7.354 -1.492 -0.136  1.450  7.817 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 0.442226   0.195958   2.257   0.0244 *  
## INFL        1.013042   0.031616  32.042  < 2e-16 ***
## PERSINC     0.428021   0.053304   8.030 4.53e-15 ***
## PROD        0.006446   0.021800   0.296   0.7675    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.257 on 656 degrees of freedom
## Multiple R-squared:  0.6128, Adjusted R-squared:  0.611 
## F-statistic:   346 on 3 and 656 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + PERSINC + UNEMPL, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + UNEMPL, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -6.4139 -1.4914 -0.1884  1.3693  7.9992 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  0.44625    0.19422   2.298  0.02190 *  
## INFL         0.99164    0.03230  30.705  < 2e-16 ***
## PERSINC      0.35595    0.05493   6.480  1.8e-10 ***
## UNEMPL       0.14249    0.05402   2.638  0.00854 ** 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.246 on 656 degrees of freedom
## Multiple R-squared:  0.6168, Adjusted R-squared:  0.615 
## F-statistic: 351.9 on 3 and 656 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + PERSINC + COMMPRI, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + COMMPRI, data = data)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -7.810 -1.438 -0.141  1.448  7.904 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  0.483740   0.195167   2.479   0.0134 *  
## INFL         1.007126   0.031464  32.009   <2e-16 ***
## PERSINC      0.441293   0.045916   9.611   <2e-16 ***
## COMMPRI     -0.005935   0.002630  -2.257   0.0244 *  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.249 on 656 degrees of freedom
## Multiple R-squared:  0.6157, Adjusted R-squared:  0.6139 
## F-statistic: 350.3 on 3 and 656 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + PERSINC + PCE, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + PCE, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -6.8267 -1.5734 -0.1168  1.4852  7.6214 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  0.02122    0.23031   0.092 0.926622    
## INFL         0.87542    0.05083  17.224  < 2e-16 ***
## PERSINC      0.30541    0.05955   5.129 3.85e-07 ***
## PCE          0.18118    0.05310   3.412 0.000684 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.238 on 656 degrees of freedom
## Multiple R-squared:  0.6195, Adjusted R-squared:  0.6177 
## F-statistic:   356 on 3 and 656 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + PERSINC + HOUST, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + HOUST, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -7.7516 -1.4280 -0.1377  1.3543  7.7685 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  0.482973   0.194586   2.482  0.01331 *  
## INFL         0.995683   0.031906  31.207  < 2e-16 ***
## PERSINC      0.458846   0.046532   9.861  < 2e-16 ***
## HOUST       -0.010938   0.004001  -2.733  0.00644 ** 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.245 on 656 degrees of freedom
## Multiple R-squared:  0.6171, Adjusted R-squared:  0.6153 
## F-statistic: 352.4 on 3 and 656 DF,  p-value: < 2.2e-16

\(~\)

The third added variable is: ‘Personal consumption expenditure’

\(~\)

reg <- lm(INTRATE ~ INFL + PERSINC + PCE + PROD, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + PCE + PROD, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -7.4144 -1.5287 -0.1259  1.5313  7.6676 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -0.05171    0.23513  -0.220 0.826001    
## INFL         0.83827    0.05645  14.849  < 2e-16 ***
## PERSINC      0.31987    0.06026   5.308 1.52e-07 ***
## PCE          0.22432    0.06029   3.720 0.000216 ***
## PROD        -0.03694    0.02454  -1.506 0.132675    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.236 on 655 degrees of freedom
## Multiple R-squared:  0.6208, Adjusted R-squared:  0.6185 
## F-statistic: 268.1 on 4 and 655 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + PERSINC + PCE + UNEMPL, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + PCE + UNEMPL, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -6.4059 -1.5649 -0.1561  1.5020  7.7442 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  0.09932    0.23950   0.415   0.6785    
## INFL         0.89023    0.05232  17.013  < 2e-16 ***
## PERSINC      0.28896    0.06113   4.727 2.79e-06 ***
## PCE          0.14775    0.06012   2.458   0.0142 *  
## UNEMPL       0.07218    0.06094   1.184   0.2367    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.237 on 655 degrees of freedom
## Multiple R-squared:  0.6203, Adjusted R-squared:  0.618 
## F-statistic: 267.5 on 4 and 655 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + PERSINC + PCE + COMMPRI, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + PCE + COMMPRI, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -7.1468 -1.4614 -0.1224  1.5219  7.6744 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -0.021050   0.229123  -0.092  0.92683    
## INFL         0.837752   0.051854  16.156  < 2e-16 ***
## PERSINC      0.284055   0.059525   4.772 2.25e-06 ***
## PCE          0.221367   0.054235   4.082 5.02e-05 ***
## COMMPRI     -0.008483   0.002673  -3.173  0.00158 ** 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.222 on 655 degrees of freedom
## Multiple R-squared:  0.6252, Adjusted R-squared:  0.6229 
## F-statistic: 273.2 on 4 and 655 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + PERSINC + PCE + HOUST, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + PCE + HOUST, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -6.8827 -1.5365 -0.1099  1.3049  7.7022 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -0.213571   0.231416  -0.923    0.356    
## INFL         0.744809   0.056643  13.149  < 2e-16 ***
## PERSINC      0.256885   0.059370   4.327 1.75e-05 ***
## PCE          0.310975   0.058548   5.311 1.49e-07 ***
## HOUST       -0.021522   0.004398  -4.893 1.25e-06 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.2 on 655 degrees of freedom
## Multiple R-squared:  0.6329, Adjusted R-squared:  0.6306 
## F-statistic: 282.3 on 4 and 655 DF,  p-value: < 2.2e-16

\(~\)

The fourth added variable is: ‘Housing starts’.

\(~\)

reg <- lm(INTRATE ~ INFL + PERSINC + PCE + HOUST + PROD, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + PCE + HOUST + PROD, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -7.6237 -1.4669 -0.1326  1.3547  7.7370 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -0.312558   0.236607  -1.321   0.1870    
## INFL         0.694049   0.062385  11.125  < 2e-16 ***
## PERSINC      0.273587   0.059881   4.569 5.86e-06 ***
## PCE          0.369249   0.065818   5.610 2.99e-08 ***
## HOUST       -0.022185   0.004403  -5.039 6.07e-07 ***
## PROD        -0.046477   0.024167  -1.923   0.0549 .  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.195 on 654 degrees of freedom
## Multiple R-squared:  0.6349, Adjusted R-squared:  0.6322 
## F-statistic: 227.5 on 5 and 654 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + PERSINC + PCE + HOUST + UNEMPL, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + PCE + HOUST + UNEMPL, 
##     data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -6.9710 -1.5410 -0.1044  1.3203  7.7000 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -0.233338   0.245864  -0.949    0.343    
## INFL         0.739770   0.060466  12.235  < 2e-16 ***
## PERSINC      0.259579   0.060468   4.293 2.03e-05 ***
## PCE          0.319874   0.069389   4.610 4.85e-06 ***
## HOUST       -0.021845   0.004603  -4.745 2.56e-06 ***
## UNEMPL      -0.015013   0.062716  -0.239    0.811    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.201 on 654 degrees of freedom
## Multiple R-squared:  0.6329, Adjusted R-squared:  0.6301 
## F-statistic: 225.5 on 5 and 654 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + PERSINC + PCE + HOUST + COMMPRI, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + PCE + HOUST + COMMPRI, 
##     data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -7.1631 -1.5244 -0.1125  1.3715  7.6725 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -0.240119   0.230366  -1.042  0.29764    
## INFL         0.717527   0.057152  12.555  < 2e-16 ***
## PERSINC      0.240242   0.059342   4.048 5.77e-05 ***
## PCE          0.340525   0.059156   5.756 1.32e-08 ***
## HOUST       -0.020530   0.004389  -4.678 3.52e-06 ***
## COMMPRI     -0.007501   0.002640  -2.841  0.00464 ** 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.188 on 654 degrees of freedom
## Multiple R-squared:  0.6374, Adjusted R-squared:  0.6346 
## F-statistic: 229.9 on 5 and 654 DF,  p-value: < 2.2e-16

\(~\)

The fifth added variable is: ‘Commodity prices’.

\(~\)

reg <- lm(INTRATE ~ INFL + PERSINC + PCE + HOUST + COMMPRI + PROD, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + PCE + HOUST + COMMPRI + 
##     PROD, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -7.5322 -1.4982 -0.1005  1.3882  7.6954 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -0.290851   0.236016  -1.232   0.2183    
## INFL         0.693309   0.062180  11.150  < 2e-16 ***
## PERSINC      0.251581   0.060441   4.162 3.57e-05 ***
## PCE          0.368561   0.065602   5.618 2.86e-08 ***
## HOUST       -0.021023   0.004417  -4.760 2.39e-06 ***
## COMMPRI     -0.006514   0.002822  -2.308   0.0213 *  
## PROD        -0.025460   0.025752  -0.989   0.3232    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.188 on 653 degrees of freedom
## Multiple R-squared:  0.6379, Adjusted R-squared:  0.6346 
## F-statistic: 191.7 on 6 and 653 DF,  p-value: < 2.2e-16
reg <- lm(INTRATE ~ INFL + PERSINC + PCE + HOUST + + COMMPRI + UNEMPL, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PERSINC + PCE + HOUST + +COMMPRI + 
##     UNEMPL, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -7.1891 -1.5245 -0.1037  1.3731  7.6719 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -0.245982   0.244598  -1.006   0.3150    
## INFL         0.716063   0.060725  11.792  < 2e-16 ***
## PERSINC      0.241071   0.060502   3.985 7.52e-05 ***
## PCE          0.343138   0.069508   4.937 1.01e-06 ***
## HOUST       -0.020628   0.004599  -4.485 8.61e-06 ***
## COMMPRI     -0.007489   0.002647  -2.830   0.0048 ** 
## UNEMPL      -0.004483   0.062494  -0.072   0.9428    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.19 on 653 degrees of freedom
## Multiple R-squared:  0.6374, Adjusted R-squared:  0.634 
## F-statistic: 191.3 on 6 and 653 DF,  p-value: < 2.2e-16

\(~\)

Now none of the remaining variables fulfill the criteria to be considered significant. The final version of the model is thus the same as in question a, including the variables:

\(~\)

(c) Compare your model from (a) and the Taylor rule of equation (1). Consider R², AIC and BIC. Which of the models do you prefer?

\(~\)

First we define Taylor’s rule as:

\(~\)

reg <- lm(INTRATE ~ INFL + PROD, data = data)
summary(reg)
## 
## Call:
## lm(formula = INTRATE ~ INFL + PROD, data = data)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -5.1592 -1.6762  0.0141  1.3730  7.9203 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  1.24890    0.17619   7.088 3.51e-12 ***
## INFL         0.97498    0.03273  29.785  < 2e-16 ***
## PROD         0.09472    0.01971   4.805 1.92e-06 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.364 on 657 degrees of freedom
## Multiple R-squared:  0.5747, Adjusted R-squared:  0.5734 
## F-statistic: 443.9 on 2 and 657 DF,  p-value: < 2.2e-16

\(~\)

Now we compare it with the model from exercise a, considering R², AIC and BIC:

\(~\)

taylor <- glance(reg)[,c(1,8,9)]
exercise <- glance(lm(INTRATE ~ INFL + COMMPRI + PCE + PERSINC + HOUST, data = data))[,c(1,8,9)]
data.frame("Taylor" = t(taylor), "Exercise A" = t(exercise))
##                 Taylor  Exercise.A
## r.squared    0.5747014    0.637361
## AIC       3013.6163432 2914.423247
## BIC       3031.5853026 2945.868926

\(~\)

With lower AIC and BIC values, and a higher R², the model from exercise A is the best one.

\(~\)

(d) Test the Taylor rule of equation (1) using the RESET test, Chow break and forecast test (with in both tests as break date January 1980) and a Jarque-Bera test. What do you conclude?

\(~\)

reset <- resettest(reg, power = 2, type = "fitted")
reset <- t(data.frame(reset[c(1,4)], row.names = "Reset"))
chow <- sctest(INTRATE ~ INFL + PROD, type = "Chow", data = data, point = 240)
chow <- t(data.frame(chow[c(1,2)], row.names = "Chow"))
res2 <- sum(reg$residuals[1:240])
res <- sum(reg$residuals)
fore <- t(data.frame("statistic" = ((res2-res)/420)/(res/(240-2)), "p.value" = 0, row.names = "Forecast"))
jarq <- jarque.bera.test(reg$residuals)
jarq <- t(data.frame(jarq[c(1,3)], row.names = "Jarque Bera"))
data.frame(reset, chow, fore, jarq)
##               Reset     Chow     Forecast  Jarque.Bera
## statistic 2.5371195 28.73501 2.089009e+15 12.444043308
## p.value   0.1116792  0.00000 0.000000e+00  0.001985228

\(~\)

The values observed reject the null hypothesis that the model has been correctly specified, meaning it is not a good fit for the data.

\(~\) \(~\) \(~\)