Stat > Basic Statistics > 2 Variances You can use the variance test to perform hypothesis tests for equality, or homogeneity, of variance among two populations using an F-test and Levene’s test. Many statistical procedures, including the two sample t-procedures, assume that the two samples are from populations with equal variance. The variance test procedure will test the validity of this assumption. Stat > ANOVA > Test for Equal VariancesUse variance test to perform hypothesis tests for equality or homogeneity of variance using Bartlett’s and Levene’s tests. An F Test replaces Bartlett’s test when you have just two levels. Many statistical procedures, including analysis of variance, assume that although different samples may come from populations with different means, they have the same variance. The effect of unequal variances upon inferences depends in part upon whether your model includes fixed or random effects, disparities in sample sizes, and the choice of multiple comparison procedure. The ANOVA F-test is only slightly affected by inequality of variance if the model contains fixed factors only and has equal or nearly equal sample sizes. F-tests involving random effects may be substantially affected, however [18]. Use the variance test procedure to test the validity of the equal variance assumption. |