Box plot

hsb2 <- read.table('http://www.ats.ucla.edu/stat/r/modules/hsb2.csv', header=T, sep=",")
attach(hsb2)

	boxplot(write)
	boxplot(write, xlab="write", boxwex=.4, col="darkblue")
	boxplot(write ~ ses)
	seslab<-as.vector(c("low","medium", "high")) sesf<-factor(ses, label=seslab) boxplot(write ~ sesf, xlab="write by ses")
	boxplot(write ~ sesf, xlab="write by ses", boxwex=.2, notch = TRUE, col = "darkblue")
	# by two factors boxplot(write ~ female + ses, xlab="write by female and ses", boxwex=.2)