Elementary Statistics Using SAS

Chapter 11 Performing Basic Regression Diagnostics

How do you determine whether your regression model adequately represents your data? How do you know when more terms should be added to the model? How do you identify outlier points, where the model doesn’t fit well? These questions can be answered using regression diagnostics. This chapter discusses the following topics:

• understanding residuals plots
• using residuals plots and lack of fit tests to decide whether to add terms to the model
• using residuals plots to identify outlier points
• using residuals plots to detect a time sequence in the data
• using studentized residuals to check for possible outliers
• checking the regression assumption for normality of residuals

Chapters 10 and 11 discuss ...