When the population standard deviations are unknown and not assumed to be equal,pooling the sample standard deviations into a single estimate of their common population value is no longer applicable.

Question

Quizplus · Accepted Answer

When population standard deviations are unknown and not assumed to be equal, it is not appropriate to pool the sample standard deviations into a single estimate of their common population value. Instead, separate estimates of the population standard deviations must be calculated for each group or sample being compared.

When the Population Standard Deviations Are Unknown and Not Assumed