x1 <- c(1,2,3,4)
y1 <- x1 + 5
x2 <- x1 + 7
y2 <- x2 – 7
x <- c(x1,x2)
y <- c(y1,y2)
postscript(“simpson.eps”, paper=”special”, width=4.5, height=3)
par(las=1)
par(mar=c(3,3,0.5,0.5))
par(mgp=c(2,1,0))
plot(x,y, cex=2, pch=21,
col=rep(c(“blue”, “red”), each=4), bg=rep(c(“lightblue”, “pink”), each=4),
xlim=range(x)+c(-2,2), ylim=range(y)+c(-2,2))
abline(lm(y1 ~ x1), col=”blue”, lwd=2)
abline(lm(y2 ~ x2), col=”red”, lwd=2)
abline(lm(y ~ x), lwd=2, lty=2)
dev.off()
