Under what condition(s) do I need to test for homoscedasticity (i.e. using the Levene's test)? Is this only for repeated-measure designs or do I need to test for this in independent designs as well?
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[This](http://www.ncbi.nlm.nih.gov/pubmed/15171807) may be worth your time (at least read the abstract) – Glen_b Jan 01 '14 at 02:07
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1[This also](http://stats.stackexchange.com/questions/305/when-conducting-a-t-test-why-would-one-prefer-to-assume-or-test-for-equal-vari). These links relate to t-tests, but the points carry over. Avoiding the question of hypothesis testing of assumptions for a moment, you rely on the assumption of constant variance when you compute standard errors, p-values or confidence/prediction intervals via the usual normal-theory procedures. – Glen_b Jan 01 '14 at 02:13
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Generally, you should try to be conscious of the assumptions of any analysis you wish to perform. If homoscedasticity is among these assumptions, you should probably test it.
Homoscedasticity is not only an assumption in repeated measures designs. For example, linear regression assumes homoscedasticity, but does not necessarily entail repeated measures.
Nick Stauner
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