In testing the difference between two population means, which of the following assumptions is not true for the two-sample procedure that uses a pooled estimate of the common variance ?
A) The two samples must be independent of each other.
B) The two samples must be small and selected at random from the populations.
C) The populations from which the samples are drawn must be t-distributed.
D) The population variances should be equal or nearly equal.
E) None of these.

Question

In testing the difference between two population means, which of the following assumptions is not true for the two-sample procedure that uses a pooled estimate of the common variance  ?
A) The two samples must be independent of each other. 
B) The two samples must be small and selected at random from the populations. 
C) The populations from which the samples are drawn must be t-distributed. 
D) The population variances should be equal or nearly equal. 
E) None of these.

Quizplus · Accepted Answer

The assumption that the populations from which the samples are drawn must be t-distributed is not true for the two-sample procedure that uses a pooled estimate of the common variance. Instead, the populations should be approximately normally distributed, and the sample sizes should be large (usually greater than 30) for the central limit theorem to work.

In Testing the Difference Between Two Population Means, Which of the Following