# Variance Assumption of ANOVAs and Parametric Tests

Listed the assumptions of ANOVAs and parametric tests.

Why do we need the equal variance assumption? What is the purpose and how does it relate to the tests/measurements used? What is the general rule about when violations of the equal variance assumption are likely to lead to serious inaccuracies in results?

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#### Solution Preview

â€¢ Many statistical techniques assume equal variance

â€¢ We have been dealing with parametric hypothesis tests, mainly the different version of the t-test

â€¢ ANOVA tests the hypothesis that the means are equal, not that variance are equal

â€¢ To assuming normality ANOVA assumes that variances are equal for each treatment.

â€¢ Models fitted by regression analysis are evaluated ...

#### Solution Summary

Variance assumptions of ANOVAs and parametric tests are analyzed.