Tests of Two Variances
When a comparison is made between two independent populations, one of the significant parameters to discover is the differentiation between variances: how much does the variation within each population differ from the other? Of course, once we've established the difference between the variances, the next step is to discover if the difference is significant. That is accomplished through a test of significance. A sample size from each population is taken: n1 and n2. We then find the variances s21 and s22 of the two samples.
A test of variances involves another type of distribution: the F-distribution.