The content of this paper consists of four parts. First, tests of homogeneity of variance, including Hartley's test, Bartlett's test, Cochran's test, Scheffe's test, and Brown-Forsythe's test. Second, problems of heterogeneous variance in t-test. Third, problems of heterogeneous variance in ANOVA. Fourth, methods to deal with unequal n and unequal variances. |