The F-distribution is parameterized by two degrees of freedom—those of the sample size and those of the number of groups.

The first degree of freedom is the count of groups less one and the second degree of freedom is the size of the sample less the number of groups. If k represents the number of groups, and n represents the sample size:

We can visualize different F-distributions with an Incanter function plot:

The lines of the preceding diagram show various F-distributions for a sample of 100 points split into 5, 10, and 50 groups.