The quantity is called the pooled variance estimate of the common variance of two unknown but equal population variances. It is the weighted average of the two sample variances, where the weights represent the:
A) sample variances.
B) sample standard deviations.
C) degrees of freedom for each sample.
D) None of these choices.

Question

The quantity  is called the pooled variance estimate of the common variance of two unknown but equal population variances. It is the weighted average of the two sample variances, where the weights represent the:
A) sample variances. 
B) sample standard deviations. 
C) degrees of freedom for each sample. 
D) None of these choices.

Quizplus · Accepted Answer

The pooled variance estimate includes the degrees of freedom for each sample as weights, since degrees of freedom are a measure of the sample size and larger sample sizes should have more influence on the pooled estimate. It does not include the actual sample variances or standard deviations as weights.

The Quantity Is Called the Pooled Variance Estimate of the Common