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 is calculated using the formula (n1-1)s1^2 + (n2-1)s2^2 / (n1 + n2 - 2), where s1^2 and s2^2 are the sample variances and n1 and n2 are the degrees of freedom for each sample. Therefore, the weights represent the degrees of freedom for each sample, making choice C the correct answer.

The Quantity Is Called the Pooled Variance Estimate of the Common