Determine the total number of all samples tested. Add the number of samples tested in each group. For example, assume you tested 10 Dell computers, 20 Hewlett-Packard computers, 30 Apple computers and 40 Gateway computers. You would have the following equation: 10 + 20 + 30 + 40 = 100.
Calculate the total number of sample groups. Continuing the same example, there are four sample groups: Dell Computers, Hewlett-Packard computers, Apple computers and Gateway computers.
Calculate the denominator degrees of freedom. Subtract the number of sample groups from Step 2 from the total number of samples tested from Step 1. From the example, the equation is 100 - 4 = 96. The solution to this equation is the answer.