\begin{Schunk}
\begin{Sinput}
 ## Step 1
 mod1age <- lm(th.bush.kerry ~ V043250, data = mydta1)
 ## Step 2
 plot(th.bush.kerry ~ V043250, type = "p", xlab = "V403250: Age", ylab = "Bush-Kerry thermometers", data = mydta1, col = gray(.7))
 ## Step 3
 abline(mod1age, lwd = 1.5)
\end{Sinput}
\end{Schunk}
