howtoplotresiduals-rcode

# howtoplotresiduals-rcode - #Illustrating various residual...

This preview shows pages 1–2. Sign up to view the full content.

Sheet1 Page 1 #Illustrating various residual plots # Model Y_i = 2 + 5*X_i + epsilon_i # Where N(0,4^2) # Fix X's from 11 to 18 set.seed(1) #This gives me the same randomly generated data every time x = runif(25,11,18) err.a = rnorm(25,0,4) y = 2 + 5*x + err.a #_____________________________________________________________________________ # Plot (a) par(mfrow=c(3,2)) #put 9 graphs on 1 page plot(x,y,main="(a) Scatter plot and regression line", cex.main=.8,pch=20,xlab="x",ylab="y") fit.a = lm(y ~ x) abline(fit.a) #_____________________________________________________________________________ # Plot (b) X vs. non-standardized residuals plot(x,fit.a\$res,pch=20, main="(b) X vs. non-standardized residuals",cex.main=.8, xlab="x",ylab="Residuals") abline(h=0) # Notice that there is no discernible pattern in the residuals. # They seem to be randomly scattered about the line y=0. #______________________________________________________________________________ # Plot (c) # Change the model so that the variance increases as x increases. err.b=err.a/2

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 06/16/2009 for the course STAT 540 taught by Professor Staff during the Spring '08 term at Colorado State.

### Page1 / 4

howtoplotresiduals-rcode - #Illustrating various residual...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online