The Related Samples t-Test

This chapter follows much the same pattern as Chap. 5 , only this time with the Related Samples t-Test. The chapter opens with a discussion of the rationale behind the Related Samples t-Test and the difference between it and the Independent Samples t-Test. We discuss the two research designs that utilize the Related Samples t-Test for analyses: the matched-pairs design and the repeated measures design, providing examples of each, and being mindful to discuss order effects and counterbalancing in reference to the repeated measures design. Going step-by-step, we walk students through the necessary calculations of the t-statistic using two examples. In the first example, we use a matched-pairs design to compare the number of errors made on a driving course when a small sample of people drive distracted versus not distracted. In the second example, we use a matched-pairs design to test whether a coping skills program reduces stress among college students. In the calculations for both examples, we demonstrate how to set up the data and calculate difference scores. Then we teach students how to apply equations for the variance, standard error of the mean difference, and the obtained value of t. We then calculate effect size using Cohen’s d and discuss the process of hypothesis testing using the t-distribution and critical values of t. Results are reported in proper APA (seventh edition) formatting. The chapter concludes with a summary of important concepts, illustrated instructions for how to compute the Related Samples t-Test using Excel’s Data Analysis Toolpak, critical thinking questions, and practice problems.