celeb <- read.csv("http://www.stat.ufl.edu/~winner/data/celebrityendorse_attention.csv") attach(celeb); names(celeb) tapply(attention,list(product,endorser),mean) tapply(attention,list(product,endorser),sd) tapply(attention,list(product,endorser),length) product <- factor(product) endorser <- factor(endorser) options(contrasts=c("contr.sum","contr.poly")) mod1 <- aov(attention ~ product*endorser) anova(mod1) summary.lm(mod1)