What type of test for population means should be performed when employees are first tested, trained, and then retested?
A) A z test under independent sampling with known population variances.
B) A t test under independent sampling with unknown but equal population variances.
C) A t test under dependent sampling.
D) A t test under independent sampling with unknown and unequal population variances.

Question

Quizplus · Accepted Answer

Since the employees are being tested, trained, and then retested, it is likely that the same population is being sampled twice (before and after training). Therefore, dependent sampling is the appropriate choice, which would use a paired t-test. Choices A and B assume independent sampling and Choices C and D assume dependent sampling, but only Choice C correctly identifies the situation as dependent sampling. Choice D is also incorrect because it assumes unequal population variances, which is not specified in the problem.

What Type of Test for Population Means Should Be Performed