Question

For an independent means t test, we calculate pooled variance for the distribution of scores from each population. Why do we do this?

Answer 1

Under the assumption of equal population variances, the pooled sample variance provides a higher precision estimate of variance than the individual sample variances. This higher precision can lead to increased statistical power when used in statistical tests that compare the populations, such as the t-test.

However, if this assumption is violated, the pooled variance estimate may not be accurate, which would affect the accuracy of our test statistic and hence, the p-value.

Hit like please.