# R-program for Exercise 27.22 of PSLS 3e

btl <- read.csv("r:/Chapter 27/ex27_022.csv")
# descriptives using doBy library
library(doBy) # package to facilitate processing by groups
summaryBy( beetles~ color, data=btl, FUN=c(length,mean,median,sd,min,max))
boxplot( beetles~ color, data=btl)

# kruskal-wallis test
kruskal.test(beetles~ as.factor(color), data=btl)

# one-way ANOVA
btl.anova <- lm(beetles~ as.factor(color), data=btl)
summary(btl.anova)
anova(btl.anova)