How To Determine If Population Variances Are Equal. Some statistical tests, for example the analysis of variance, assume that variances are equal across groups or samples. Generally the range is considered to be too easily influenced by extreme values, so the iqr is preferred.
However, if this assumption is violated, the pooled variance estimate may not be accurate, which would affect the accuracy of our test statistic (and hence, the p. This test does not assume that the variances of both populations are equal. Μ x = μ y) against any of the alternative hypotheses:
