Structure
## Loading required package: Formula
##
## Attaching package: 'plm'
## The following object is masked from 'package:data.table':
##
## between
pdfwagepan <- pdata.frame(wagepan,index=c('nr','year'))
Pooled OLS
model1 <- plm(lwage~educ+exper,model="pooling",data=pdfwagepan)
summary(model1)
## Pooling Model
##
## Call:
## plm(formula = lwage ~ educ + exper, data = pdfwagepan, model = "pooling")
##
## Balanced Panel: n = 545, T = 8, N = 4360
##
## Residuals:
## Min. 1st Qu. Median 3rd Qu. Max.
## -5.332208 -0.259202 0.034226 0.308498 2.514500
##
## Coefficients:
## Estimate Std. Error t-value Pr(>|t|)
## (Intercept) 0.0120541 0.0626042 0.1925 0.8473
## educ 0.1078844 0.0045477 23.7228 <2e-16 ***
## exper 0.0564295 0.0028102 20.0806 <2e-16 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Total Sum of Squares: 1236.5
## Residual Sum of Squares: 1059.8
## R-Squared: 0.14289
## Adj. R-Squared: 0.1425
## F-statistic: 363.191 on 2 and 4357 DF, p-value: < 2.22e-16
Fixed effects (Within groups)
model2 <- plm(lwage~educ+exper,model="within",data=pdfwagepan)
summary(model2)
## Oneway (individual) effect Within Model
##
## Call:
## plm(formula = lwage ~ educ + exper, data = pdfwagepan, model = "within")
##
## Balanced Panel: n = 545, T = 8, N = 4360
##
## Residuals:
## Min. 1st Qu. Median 3rd Qu. Max.
## -4.148013 -0.124958 0.013642 0.161298 1.505558
##
## Coefficients:
## Estimate Std. Error t-value Pr(>|t|)
## exper 0.0633278 0.0023454 27 < 2.2e-16 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Total Sum of Squares: 572.05
## Residual Sum of Squares: 480.25
## R-Squared: 0.16047
## Adj. R-Squared: 0.040508
## F-statistic: 729.027 on 1 and 3814 DF, p-value: < 2.22e-16
summary(c(fixef(model2)))
## Min. 1st Qu. Median Mean 3rd Qu. Max.
## -0.01496 0.94959 1.23988 1.23659 1.52607 2.88920
model3 <- plm(lwage~educ+exper,model="within",effect="time",data=pdfwagepan)
summary(model3)
## Oneway (time) effect Within Model
##
## Call:
## plm(formula = lwage ~ educ + exper, data = pdfwagepan, effect = "time",
## model = "within")
##
## Balanced Panel: n = 545, T = 8, N = 4360
##
## Residuals:
## Min. 1st Qu. Median 3rd Qu. Max.
## -5.351880 -0.262312 0.028272 0.305250 2.460275
##
## Coefficients:
## Estimate Std. Error t-value Pr(>|t|)
## educ 0.0969287 0.0052413 18.4934 < 2.2e-16 ***
## exper 0.0364743 0.0055347 6.5901 4.92e-11 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Total Sum of Squares: 1143.6
## Residual Sum of Squares: 1054.4
## R-Squared: 0.077944
## Adj. R-Squared: 0.076037
## F-statistic: 183.859 on 2 and 4350 DF, p-value: < 2.22e-16
model4 <- plm(lwage~educ+exper+as.factor(year),model="within",data=pdfwagepan)
summary(model4)
## Oneway (individual) effect Within Model
##
## Call:
## plm(formula = lwage ~ educ + exper + as.factor(year), data = pdfwagepan,
## model = "within")
##
## Balanced Panel: n = 545, T = 8, N = 4360
##
## Residuals:
## Min. 1st Qu. Median 3rd Qu. Max.
## -4.157497 -0.124763 0.010873 0.160003 1.503777
##
## Coefficients: (1 dropped because of singularities)
## Estimate Std. Error t-value Pr(>|t|)
## exper 0.06757176 0.00306957 22.0135 < 2e-16 ***
## as.factor(year)1981 0.05181844 0.02012850 2.5744 0.01008 *
## as.factor(year)1982 0.04304658 0.01916944 2.2456 0.02479 *
## as.factor(year)1983 0.02307119 0.01867145 1.2356 0.21667
## as.factor(year)1984 0.02653105 0.01867145 1.4209 0.15542
## as.factor(year)1985 0.00807450 0.01916944 0.4212 0.67362
## as.factor(year)1986 0.00081119 0.02012850 0.0403 0.96786
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Total Sum of Squares: 572.05
## Residual Sum of Squares: 479.09
## R-Squared: 0.16251
## Adj. R-Squared: 0.041334
## F-statistic: 105.563 on 7 and 3808 DF, p-value: < 2.22e-16
Arellano correction
## HAC estimator. Note: n must be >> T
summary(model2,plm::vcovHC)
## Oneway (individual) effect Within Model
##
## Note: Coefficient variance-covariance matrix supplied: plm::vcovHC
##
## Call:
## plm(formula = lwage ~ educ + exper, data = pdfwagepan, model = "within")
##
## Balanced Panel: n = 545, T = 8, N = 4360
##
## Residuals:
## Min. 1st Qu. Median 3rd Qu. Max.
## -4.148013 -0.124958 0.013642 0.161298 1.505558
##
## Coefficients:
## Estimate Std. Error t-value Pr(>|t|)
## exper 0.0633278 0.0032464 19.507 < 2.2e-16 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Total Sum of Squares: 572.05
## Residual Sum of Squares: 480.25
## R-Squared: 0.16047
## Adj. R-Squared: 0.040508
## F-statistic: 380.531 on 1 and 544 DF, p-value: < 2.22e-16