ABSTRACT

This chapter presents information about a one-way within-groups Analysis of variance (ANOVA). For within-groups ANOVA, scores for each subject appear in all levels of the independent variable in a one-way design. Instead of the independence assumption, within-groups ANOVA requires the sphericity assumption, which relates to the variances, the correlations, and score differences from all of the levels of the independent variable. Statistical Package for the Social Sciences tests the assumption for people by using Mauchly's test of sphericity, a test of whether the sphericity assumption has been met. Multiple comparison tests are appropriate only for fixed independent variables. Fixed variables are ones for which the researcher has selected the levels rather than allow the levels to be selected at random. The use of repeated-measures design is to determine whether significant differences exist among the means of the levels of the independent variable when subjects are measured repeatedly.