Introduction to Statistical Sample Size Concepts

Determining the appropriate sample size for a study is very important to the design of an investigation. The sample size must be correctly chosen to allow a study to arrive at valid conclusions. A study which is too small may produce inconclusive results, while a study which is too large will waste scarce resources.

This section of nQuery Advisor eTutor presents a brief introduction to sample size determination concepts for significance testing of a null hypothesis (two-group t-test), confidence intervals and non-inferiority or equivalence testing. It includes sample output from nQuery Advisor to illustrate the concepts under discussion and tests the users understanding of these concepts with a series of multiple choice questions.