Question

A significance test is to be conducted concerning population means and based on the difference between the two sample means . What assumptions are required in order for the two-sample z statistic to be valid

Answer 1

In order for the two-sample z statistic to be valid we need that the following assumptions hold:

• each sample and population must be independent from each other
• each population must be normally distributed
• the population standard deviations must be known or the sample sizes must be ≥ 30
• samples must be random
• data has to be continuous