A z-test is statistical test used to determine whether two population means are different when the variances are known and the sample size is large. What Is a Z-Test? A z-test is a statistical test ...

This article shows how one should properly conduct a paired-sample comparison of means in a test-retest situation where only a subset of the population retakes the exam. For example, suppose all who ...

This is a preview. Log in through your library . Abstract The analysis of paired data with a variable number of readings per pairing is discussed. The standard t-test based on paired means is not ...