Next section: Two estimates of variance

This means that the probability values computed in an ANOVA are satisfactorily accurate even if the assumptions are violated. Moreover, ANOVA tends to be conservative when its assumptions are violated. This means that although power is decreased, the probability of a Type I error is as low or lower than it would be if its assumptions were met. There are exceptions to this rule. For example, a combination of unequal sample sizes and a violation of the assumption of homogeneity of variance can lead to an inflated Type I error rate.

Next section: Two estimates of variance