The degrees of freedom for a t test of the difference of population means from two independent samples are n1 + n2 - 2.

Question

Quizplus · Accepted Answer

This is a true statement. The degrees of freedom for a t test of the difference of population means from two independent samples are equal to the sum of the sample sizes minus 2. This reflects the fact that there are two sample means being compared, and therefore some of the information from one sample can be used to estimate the variability in the other sample. The formula for degrees of freedom is often written as df = n1 + n2 - 2.

The Degrees of Freedom for a T Test of the Difference