in an analysis of variance, a value formed from the ratio of the largest variance over the smallest variance from the set of groups being assessed. The Fmax statistic is assessed for significance by looking up the critical value in a statistical table for the relevant number of groups and degrees of freedom. If the calculated Fmax statistic is larger than the critical valve, then there is evidence of heterogeneity of variance, which violates one of the assumptions of the analysis and renders its results invalid.