If the sample sizes are not equal,then the pooled variance estimate should be calculated ____.
A)using the unweighted mean of the variances
B)using a weighted mean of the variances
C)by reducing the size of one group to equal the size of the other group

Question

Quizplus · Accepted Answer

When sample sizes are not equal, the pooled variance estimate should be calculated using a weighted mean of the variances, with the weights being the degrees of freedom of each group minus one. This is because the group with a larger sample size has a greater influence on the overall variance estimate, so it should be weighted more heavily in the calculation of the pooled variance. Using the unweighted mean of the variances or reducing the size of one group to equal the other group would not result in an accurate estimate of the overall variance.

If the Sample Sizes Are Not Equal,then the Pooled Variance