After reading this chapter, you should be able to:

1. Explain why a t distribution is associated with n − 1 degrees of freedom and describe the information that is conveyed by the t statistic.
2. Calculate the degrees of freedom for a one-sample t test and a two-independent-sample t test, and locate critical values in the t table.
3. Identify the assumptions for the one-sample t test.
4. Compute a one-sample t test and interpret the results.
5. Compute and interpret effect size and proportion of variance for a one-sample t test.
6. Identify the assumptions for the two-independent-sample t test.
7. Compute a two-independent-sample t test and interpret the results.
8. Compute and interpret effect size and proportion of variance for a two-independent-sample t test.
9. Summarize the results of a one-sample t test and a two-independent-sample t test in APA format.
10. Compute a one-sample t test and a two-independent-sample t test using SPSS.