As might be expected, the inclusion of more than one explanatory variable in a linear regression model adds to the complexity of the analyses of such models. The assessment of four issues are addressed in this chapter: structural violations, multicollinearity, variable selection, and model selection. For the most part, the model for the dataset MultipleReg from Chapter 8

is used in the following illustrations. Where appropriate, additional datasets are generated. Begin this chapter by first clearing the work space, then recall

At this point, "MultipleReg" should be the only object in the workspace.