A confidence interval for the difference of two population means:
A)must pool the sample variances.
B)may or may not pool the sample variances.
C)cannot be used to test for equal population means.

Question

Quizplus · Accepted Answer

When the population variances are equal and the sample sizes are similar, the sample variances can be pooled for a more precise estimate of the population variance. However, when the population variances are not equal, or the sample sizes are significantly different, it is better not to pool the variances. Therefore, confidence intervals for the difference of two population means may or may not pool the sample variances depending on whether the sample sizes are similar and the population variances are equal. Also, confidence intervals for the difference of two population means can be used to test for equal population means by checking if the interval contains zero.

A Confidence Interval for the Difference of Two Population Means