ABSTRACT
In this chapter, the authors explore within-subjects designs. The simplest of the designs is the paired samples design. The difference between between-subjects designs and within-subjects designs is the nature of the independent variable. The designs are called within-subjects because we are comparing data points from the same participants rather than comparing groups of participants. In other tests so far, the test statistic has been a ratio of between-subjects variation over within-subjects variation or error. As a result, the paired samples t-test will be a ratio of variance between the levels of the within-subjects variable over the variance within levels of the within-subjects variable. Interpreting the pattern of difference is perhaps the simplest step in the paired samples t-test. The within-subjects independent variable has only two levels. The t-test result showed us that the difference between those two levels was statistically significant.
