Question

Write the test statistic for testing the equality of two SDs.

Answer 1

Answer:

Assuming equal variances, the test statistic is calculated as: - where x bar 1 and x bar 2 are the sample means, s² is the pooled sample variance, n1 and n2 are the sample sizes and t is a Student t quantile with n1 + n2 - 2 degrees of freedom.

Answer 2

An F-test (Snedecor and Cochran, 1983) is used to test if the variances of two populations are equal. This test can be a two-tailed test or a one-tailed test. The two-tailed version tests against the alternative that the variances are not equal.