Biostatistics by Example Using SAS Studio

Chapter 14: Computing Power and Sample Size

Introduction

Computing Sample Size for a t Test

Calculating the Sample Size for a Test of Proportions

Computing Sample Size for a One-Way ANOVA Design

Conclusions

Problems

Introduction

In my 26 years as a biostatistician at the Rutgers Robert Wood Johnson Medical School in New Jersey, the most frequent question I was asked was "I'm doing an experiment, how many subjects do I need?" Just about any study, especially one for which you are asking for funding or applying for a grant, will require detailed power and sample size calculations.

For those readers a bit rusty on this subject, the power of a study is the probability that the study will result in a statistically significant finding if the drug or ...