In order to construct an interval estimate of the difference in the means of two normally distributed populations with unknown but equal variances, using two independent samples of size n₁ and n₂, we must use a t distribution with (n₁+ n₂-1)degrees of freedom.

Question

Quizplus · Accepted Answer

When the variances are assumed to be equal, the degrees of freedom for the t distribution should be (n₁ + n₂ - 2), not (n₁ + n₂ - 1).

In Order to Construct an Interval Estimate of the Difference