\begin{Schunk}
\begin{Sinput}
 dat$y5 <- dat$y + rnorm(length(dat$y), sd = 30)
 mod5 <- lm(y5 ~ x1, data = dat)
 plotSlopes(mod5, plotx = "x1", interval = "confidence", plotLegend = F, xlim = c(0, 1.05 * max(dat$x1)), axes = F)
 axis(1)
 axis(2, pos = 0)
 axis(2, pos = mean(dat$x1), labels = FALSE)
 arrows(0.3, 1.15*mean(dat$y5), 0.80 * mean(dat$x1), 1.2*mean(dat$y5), col = "red")
\end{Sinput}
\end{Schunk}
