In testing the difference between two population means using two independent samples, under which of the following conditions would we use the pooled variance in estimating the standard error of the sampling distribution of the sample mean difference ?
A) The sample sizes are both large.
B) The populations are normal with equal variances.
C) The populations are non-normal with unequal variances.

Question

In testing the difference between two population means using two independent samples, under which of the following conditions would we use the pooled variance in estimating the standard error of the sampling distribution of the sample mean difference  ?
A) The sample sizes are both large. 
B) The populations are normal with equal variances. 
C) The populations are non-normal with unequal variances.

Quizplus · Accepted Answer

When testing the difference between two population means using two independent samples, we use the pooled variance in estimating the standard error of the sampling distribution of the sample mean difference when the populations are normal with equal variances. This allows us to combine information from both samples to obtain a more precise estimate of the population variance.

In Testing the Difference Between Two Population Means Using Two