Common Statistical Methods for Clinical Research with SAS Examples, Second Edition, written by Glenn Walker, provides clinical researchers with an invaluable aid for understanding the statistical methods cited most frequently in clinical protocols, statistical analysis plans, clinical and statistical reports, and medical journals. The text is written in a way that takes the non-statistician through each test using examples, yet substantive details are presented that benefit even the most experienced data analyst. Introductory chapters provide elementary statistical concepts as applied to clinical trials and an overview of statistical inference, including discussions about power, calculating sample size, p-values, and the logic behind hypothesis testing. The statistical methods discussed here represent a composite of methods most commonly used in the analysis of clinical research data. Numerous examples taken from clinical research show how to calculate statistical data both manually and using SAS. This revised edition includes sections about crossover designs and multiple comparison methods, a discussion of interim analyses, 50% more examples, and reader exercises. Extensions of methods previously presented only in their most elementary form are shown in new examples.