Duncan1 <- read.table("c:/temp/Duncan.txt",header=T)
names(Duncan1)

Duncan1.lmedinc <- lm(prestige ~ income +education , data=Duncan1)

summary(Duncan1.lmedinc)

 # This code illustrates the use of partial regression plots in R

library(car)

 # from the car library, the av.plots function produces partial regression plots 
 # (also known as added variable plots, or av.plots)

av.plots(Duncan1.lmedinc,one.page=TRUE,ask=FALSE,identify.points=FALSE)