Page 344 - Applied Statistics with R

344 CHAPTER 14. TRANSFORMATIONS

= exp( + ) ⋅ exp( )

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1

plot(salary ~ years, data = initech, col = "grey", pch = 20, cex = 1.5,
main = "Salaries at Initech, By Seniority")
curve(exp(initech_fit_log$coef[1] + initech_fit_log$coef[2] * x),
from = 0, to = 30, add = TRUE, col = "darkorange", lwd = 2)

Salaries at Initech, By Seniority

250000

salary 150000

50000

5 10 15 20 25

years

par(mfrow = c(1, 2))

plot(fitted(initech_fit_log), resid(initech_fit_log), col = "grey", pch = 20,
xlab = "Fitted", ylab = "Residuals", main = "Fitted versus Residuals")
abline(h = 0, col = "darkorange", lwd = 2)

qqnorm(resid(initech_fit_log), main = "Normal Q-Q Plot", col = "darkgrey")
qqline(resid(initech_fit_log), col = "dodgerblue", lwd = 2)