Hartley's Fmax is a statistic used to compare variances across groups. It is also commonly referred to as which of the following?

• A. Mean Square Ratio
• B. Fmax Test
• C. F-Ratio
• D. Variance Ratio

Answer: (D)

This statistic is all about the spread of the groups, using the largest variance in the numerator and the smallest variance in the denominator. Because it literally measures a ratio of variances, the standard name for it is the variance ratio. It isn’t the same as the ANOVA F statistic, which uses a ratio of mean squares, and while some people might call it an Fmax test, the conventional label you’ll see in texts is variance ratio.