\begin{Schunk}
\begin{Sinput}
 plot(RATINGS ~ GRIP, data=dat, xlab="Grip Strength", ylab="Supervisor Rating")
 abline(mod1)
 newdf <- data.frame(GRIP=plotSeq(dat$GRIP, 20))
 pconf <- predict(mod1, interval="confidence", newdata=newdf)
 lines(newdf$GRIP, pconf[, "lwr"], lty=4, col="red")
 lines(newdf$GRIP, pconf[, "upr"], lty=4, col="red")
 legend("topright", legend=c("predicted","lower CI","upper CI"), lty=c(1,4,4), col=c("black", "red","red"))
\end{Sinput}
\end{Schunk}
