Why Is It Necessary to Use the Pooled Variance When

Multiple Choice

Why is it necessary to use the pooled variance when conducting an independent-samples t test?

A) We are working with two samples, and an estimate of spread based on two samples is likely to be more accurate than an estimate of spread based on a single sample.
B) It is necessary to estimate the standard deviation of the two samples in order to compare the two samples to one another.
C) Estimating the spread of the sample using the standard deviation increases the generalizability of results.
D) Using the pooled variance helps the researcher identify skewness.