Recall that the pooled variance in the t-statistic formula is obtained by averagingtogether the two sample variances. It makes sense to average these two values only ifthey both are estimating the same population variance—that is, if the homogeneity ofvariance assumption is satisfied. If the two sample variances are estimating differentpopulation variances, then the average is meaningless. (Note: If two people are askedto estimate the same thing—for example, what your IQ is—it is reasonable to averagethe two estimates. However, it is not meaningful to average estimates of two differentthings. If one person estimates your IQ and another estimates the number of grapes ina pound, it is meaningless to average the two numbers.)Homogeneity of variance is most important when there is a large discrepancy