pdf("ballistic1.pdf") ballistic1 <- read.fwf("http://www.stat.ufl.edu/~winner/data//ballistic1.dat", width=c(8,8,8,8,8), col.names=c("bulltype", "layers", "v50", "sharp", "fsp")) v502=ballistic1$v50*ballistic1$v50/10000 ballistic <- data.frame(ballistic1, v502) attach(ballistic) ballistic.reg1 <- lm(v502 ~ layers + sharp + fsp + I(layers*sharp) + I(layers*fsp)) summary(ballistic.reg1) aov(ballistic.reg1) infl.reg1 <- influence.measures(ballistic.reg1) infl.reg1 rstres.reg1 <- rstudent(ballistic.reg1) rstres.reg1 ballistic.reg2 <- lm(v502 ~ layers + sharp + fsp) summary(ballistic.reg2) aov(ballistic.reg2) ballistic.reg3 <- lm(v502 ~ layers) summary(ballistic.reg3) aov(ballistic.reg3) anova(ballistic.reg2,ballistic.reg1) anova(ballistic.reg3,ballistic.reg2) anova(ballistic.reg3,ballistic.reg1) dev.off()