Preface to First Edition - lib

60 SIMPLE INFERENCE1 R> nf psymb plot(mortality ~ hardness, data = water, pch = psymb)5 R> abline(lm(mortality ~ hardness, data = water))6 R> legend("topright", legend = levels(water$location),7 + pch = c(1,2), bty = "n")8 R> hist(water$hardness)9 R> boxplot(water$mortality)Histogram of water$hardnessFrequencymortality0 150 20 40 60 80 100 120 140water$hardness1200 1400 1600 1800 2000NorthSouth1200 1400 1600 1800 20000 20 40 60 80 100 120 140hardnessFigure 3.8Enhanced scatterplot of water hardness and mortality, showing boththe joint and the marginal distributions and, in addition, the locationof the city by different plotting symbols.© 2010 by Taylor and Francis Group, LLC