library(faraway) data(composite) summary(composite) g <- lm(strength ~ laser + tape, composite) with(composite,interaction.plot(laser,tape,strength,legend=F)) with(composite,interaction.plot(tape,laser,strength,legend=F)) coef(g) lasercoefs <- rep(c(0,6.5733,12.2133),3) tapecoefs <- rep(c(0,4.0367,-1.4800),each=3) h <- update(g, . ~ . + I(lasercoefs*tapecoefs)) anova(h) anova(g) composite$laser <- as.ordered(composite$laser) composite$tape <- as.ordered(composite$tape) g <- lm(strength ~ laser + tape, composite) summary(g) contr.poly(3) composite$Ntape <- rep(c(6.42,13,27),each=3) composite$Nlaser <- rep(c(40,50,60),3) gl <- lm(strength ~ Nlaser + poly(log(Ntape),2), composite) summary(gl) data(pvc) attach(pvc) stripchart(psize ~ resin,xlab="Particle size",ylab="Resin railcar") stripchart(psize ~ operator,xlab="Particle size",ylab="Operator") interaction.plot(operator,resin,psize) interaction.plot(resin,operator,psize) g <- lm(psize ~ operator*resin) anova(g) anova(lm(psize ~ operator + resin, pvc)) qqnorm(residuals(g)) qqline(residuals(g)) plot(fitted(g),residuals(g),xlab="Fitted",ylab="Residuals") g <- lm(psize ~ operator+resin,subset=-45) summary(g) TukeyHSD(aov(psize ~ operator+resin,subset=-45)) data(speedo) speedo g <- lm(y ~ .,speedo) summary(g) model.matrix(g) qqnorm(coef(g)[-1],pch=names(coef(g)[-1])) halfnorm(coef(g)[-1],labs=names(coef(g)[-1]))