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PART II

One-and Two-Sample Difference Tests

Chapter 6 Introduction to Hypothesis Testing

Chapter 7 The Single-Sample t Test

Chapter 8 Independent-Samples t Test

Chapter 9 The Paired-Samples t Test

The four chapters in this section form the core of statistics for psychology. First, hypothesis testing is introduced. Hypothesis testing is the procedure that statisticians use to make decisions that are objective and data-based, not subjective and emotion-based.

Then the most commonly used tool in the psychologist’s toolbox, the difference test, is introduced in several varieties. Single-sample difference tests are used to answer questions such as the following: Is the average GPA in this sample of students different from the mean GPA for the entire population of students? Two-sample difference tests are used to answer questions like those posed by classic experiments that have one experimental group and one control group. In this section, we’ll learn about two, the independent-samples t test and the paired-samples t test. In the next section, we’ll cover ANOVA, tests used in more complex situations when experiments include three or more groups.