RGraphGallery

• example how a the diagnostic plot no 1 looks if the error variance is not constant (strong non-constant variance)

par(mfrow=c(3,3)) ## 9 plots on one page
x <- runif(100,0,20)
for(i in 1:9){
  y <- x + x * rnorm(100)
  m <- lm(y ~ x)
  plot(m,which=1)
}