Examples
Example 2.3
setwd("/Users/vancam/Documents/WAIKATO-Thesis/Rworking/Wooldridge/StataFile")
library(foreign)
ceosal1 <- read.dta("CEOSAL1.DTA")
## Warning in read.dta("CEOSAL1.DTA"): cannot read factor labels from Stata 5
## files
ceoreg <- lm(data= ceosal1, salary~roe)
summary(ceoreg)
##
## Call:
## lm(formula = salary ~ roe, data = ceosal1)
##
## Residuals:
## Min 1Q Median 3Q Max
## -1160.2 -526.0 -254.0 138.8 13499.9
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) 963.19 213.24 4.517 1.05e-05 ***
## roe 18.50 11.12 1.663 0.0978 .
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 1367 on 207 degrees of freedom
## Multiple R-squared: 0.01319, Adjusted R-squared: 0.008421
## F-statistic: 2.767 on 1 and 207 DF, p-value: 0.09777
Example 2.4
wage1 <- read.dta("WAGE1.DTA")
## Warning in read.dta("WAGE1.DTA"): cannot read factor labels from Stata 5
## files
wagereg <- lm(data = wage1, wage~educ)
summary(wagereg)
##
## Call:
## lm(formula = wage ~ educ, data = wage1)
##
## Residuals:
## Min 1Q Median 3Q Max
## -5.3396 -2.1501 -0.9674 1.1921 16.6085
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) -0.90485 0.68497 -1.321 0.187
## educ 0.54136 0.05325 10.167 <2e-16 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 3.378 on 524 degrees of freedom
## Multiple R-squared: 0.1648, Adjusted R-squared: 0.1632
## F-statistic: 103.4 on 1 and 524 DF, p-value: < 2.2e-16
Example 2.5
vote1 <- read.dta("VOTE1.DTA")
## Warning in read.dta("VOTE1.DTA"): cannot read factor labels from Stata 5
## files
votereg <- lm(data = vote1, voteA~shareA)
summary(votereg)
##
## Call:
## lm(formula = voteA ~ shareA, data = vote1)
##
## Residuals:
## Min 1Q Median 3Q Max
## -16.8919 -4.0660 -0.1682 3.4965 29.9772
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) 26.81221 0.88721 30.22 <2e-16 ***
## shareA 0.46383 0.01454 31.90 <2e-16 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 6.385 on 171 degrees of freedom
## Multiple R-squared: 0.8561, Adjusted R-squared: 0.8553
## F-statistic: 1018 on 1 and 171 DF, p-value: < 2.2e-16
Example 2.10
logwagereg <- lm(data = wage1, log(wage)~educ)
summary(logwagereg)
##
## Call:
## lm(formula = log(wage) ~ educ, data = wage1)
##
## Residuals:
## Min 1Q Median 3Q Max
## -2.21158 -0.36393 -0.07263 0.29712 1.52339
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) 0.583773 0.097336 5.998 3.74e-09 ***
## educ 0.082744 0.007567 10.935 < 2e-16 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 0.4801 on 524 degrees of freedom
## Multiple R-squared: 0.1858, Adjusted R-squared: 0.1843
## F-statistic: 119.6 on 1 and 524 DF, p-value: < 2.2e-16
Example 2.11
logceoreg <- lm(data = ceosal1, log(salary)~log(sales))
summary(logceoreg)
##
## Call:
## lm(formula = log(salary) ~ log(sales), data = ceosal1)
##
## Residuals:
## Min 1Q Median 3Q Max
## -1.01038 -0.28140 -0.02723 0.21222 2.81128
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) 4.82200 0.28834 16.723 < 2e-16 ***
## log(sales) 0.25667 0.03452 7.436 2.7e-12 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 0.5044 on 207 degrees of freedom
## Multiple R-squared: 0.2108, Adjusted R-squared: 0.207
## F-statistic: 55.3 on 1 and 207 DF, p-value: 2.703e-12
Example 2.12
meap93 <- read.dta("MEAP93.DTA")
## Warning in read.dta("MEAP93.DTA"): cannot read factor labels from Stata 5
## files
meap93reg <- lm(data = meap93, math10~lnchprg)
summary(meap93reg)
##
## Call:
## lm(formula = math10 ~ lnchprg, data = meap93)
##
## Residuals:
## Min 1Q Median 3Q Max
## -24.386 -5.979 -1.207 4.865 45.845
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) 32.14271 0.99758 32.221 <2e-16 ***
## lnchprg -0.31886 0.03484 -9.152 <2e-16 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 9.566 on 406 degrees of freedom
## Multiple R-squared: 0.171, Adjusted R-squared: 0.169
## F-statistic: 83.77 on 1 and 406 DF, p-value: < 2.2e-16
plot(math10~lnchprg, data = meap93)
library(ggplot2)
ggplot(meap93, aes(math10, lnchprg)) + geom_point() + geom_smooth(method = "lm")
