Try this for starters: X1<-c(25, 50, 100, 200, 400) Y1<-c(77.7, 78, 64.3, 59.7, 51.2)
X2<-c(25, 50, 100, 200) Y2<-c(77.7, 52.3, 23.7, 6) dat1 <- data.frame(X=X1,Y=Y1,f='D1') dat2 <- data.frame(X=X2,Y=Y2,f='D2') dat <- rbind(dat1,dat2) model <- lm(Y~X*f,data=dat) summary(model) # Test H_0: fD2=0 for difference in intercept # Test H_0: X:fD2=0 for difference in slopes. # Don't forget this test! anova(lm(Y~X,data=dat),lm(Y~X*f,data=dat)) library(ggplot2) ggplot(data=dat,aes(x=X,y=Y,group=f))+geom_point(aes(colour=f))+xlim(0,400)+geom_abline(intercept=77.175,slope=-0.07094)+geom_abline(intercept=(77.175-1.54022), slope=(-.07094-.30997)) Nicholas _______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-sig-teaching
