If the sample sizes are small, but the populations are normally distributed and the population variances are known, the z-statistic can be used as the basis for statistical inferences about the difference in two population means using two independent random samples.

Question

Quizplus · Accepted Answer

The z-statistic can be used when the population variances are known, regardless of sample size, as long as the populations are normally distributed.

If the Sample Sizes Are Small, but the Populations Are