ABSTRACT
This chapter introduces the first group comparison test covered in this text: the independent samples t-test. This test allows for the comparison of two groups or samples. The simple test for evaluating homogeneity of variance is Levene's test. It is automatically produced by SPSS software with the independent samples t-test. Omega squared is best interpreted in the context of the literature too. However, there is a really plain, meaningful interpretation of the effect size estimate available. In the case of the independent samples t-test, it represents the proportion of variance on the dependent variable that was explained by group membership on the independent variable. The numerator is the mean difference, which in the case of the independent samples t-test is the difference between the two groups' means. The denominator is the standard error, which in our case will be the square root of the pooled variance.
