\begin{Schunk}
\begin{Sinput}
 library(rockchalk)
 ## harvest lm information, ignore drawing
 lm1ps <- plotSlopes(lm1, plotx = "x1")
 plotCurves(glm1, plotx = "x1", plotLegend = FALSE) 
 lines(fit ~ x1, data = lm1ps$newdata, col = "green")
 legend("topright", legend = c("GLM log link", "OLS"), col = c("black", "green"), lty = c(1,1))
\end{Sinput}
\end{Schunk}
