Chapter 13

More Complicated Testing

IN THIS CHAPTER

check Working with two variables

check Working with replications

check Understanding interactions

check Mixing variable types

check Working with multiple dependent variables

In Chapter 11, I show you how to test hypotheses with two samples. In Chapter 12, I show you how to test hypotheses when you have more than two samples. The common thread in both chapters is one independent variable (also called a factor).

Many times, you have to test the effects of more than one factor. In this chapter, I show how to analyze two factors within the same set of data. Several types of situations are possible, and I describe R functions that deal with each one.

Cracking the Combinations

Imagine that a company has two methods of presenting its training information: One is via a person who presents the information orally, and the other is via a text document. Imagine also that the information is presented in either a humorous way or a technical way. I refer to the first factor ...

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