t-test for Dependent Samples - More Complex Group Comparisons

If there are more than two "correlated samples" (example, before treatment, after treatment 1, and after treatment 2), then analysis of variance with repeated measures should be used. The repeated measures ANOVA can be considered a generalization of the t-test for dependent samples, and it offers various features that increase the overall sensitivity of the analysis. For example, it can simultaneously control not only for the base level of the dependent variable, but it can control for other factors and include in the design more than one interrelated dependent variable (MANOVA; for additional details refer General Linear Models (GLM) or ANOVA/MANOVA).