How do you test equality of variances?

medium

Answer

$Bartlett: assumes normality; sensitive to non-normality.$
$Levene: uses absolute deviations from mean or median (Brown-Forsythe uses median); more robust.$
$F-test of variances: strictly two-sample under normality.$
$Use Levene (with median) as the safe default.$
$Purpose: check equal-variance assumption for ANOVA / pooled t-test; if violated, use Welch's variants.$

Check yourself — multiple choice

Same test
Bartlett: normality-sensitive; Levene (mean or median-based): robust default; needed to check ANOVA / t-test equal-variance assumption
Only F-test
Never useful

Equal-variance tests: Levene (robust default); Bartlett (normal-sensitive).

#hypothesis-testing#parametric-tests

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