\begin{Schunk}
\begin{Sinput}
 plot(sei~educ, data=dat, cex=0.5,main="", xlab="Education (years)", ylab="Socio-economic Status",ylim=c(0,120), type="n")
 points(dat$educ, dat$sei, col=c("black", "gray60"), pch=c(1, 4))
 legend("topleft", legend=c("Male","Female"), col=c("black","gray80"), pch=c(1,4))
\end{Sinput}
\end{Schunk}
