The plot should have no obvious pattern (so random data points is evidence of no violation of the assumption). The GLM procedures provide a scatterplot of “spread versus level plot”.Hartley’s F-max test is favoured by some researchers, while others argue that it is extremely sensitive to violations of normality.The Bartlett’s test of homogeneity of variance has largely been replaced by the Levene’s test.The recommendation is that when the Levene’s test is significant (indicating a violation of the assumption of homogeneity of variance), then use Brown & Forsythe’s test and if this is also significant, then accept and report the results of the latter. The Brown & Forsythe’s test of homogeneity of variances is also generally more robust than the Levine’s test when group sizes are highly unequal and with highly skewed data.The Welch test could be better when group sample sizes are highly unequal.In either case, the Levene’s and Box’s M tests should be non-significant. MANOVA), it involves variance/covariance matrices so we need to use the Box’s M test to test for homoscedasticity. With a multivariate procedure (where we have more than one metric dependent variable, e.g. Levene’s test is the most commonly used with a single metric dependent variable.
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