Clinical Trials

■■❚❙❘Chapter 20Comparisonof ProportionsDuolao Wang, Tim Clayton, and Felicity ClemensIn clinical trials, patients’ responses to treatments are oftenrecorded according to the occurrence of some meaningfuland well-defined event such as death, cure, or reduction inseverity of disease. These records generate efficacy andsafety endpoints in the form of categorical data on eithera nominal (specific named outcome) or ordinal scale,which are often summarized by proportions or percentagesby treatment groups (or frequency tables) and displayedgraphically using bar or pie charts. In this chapter, weintroduce some fundamental concepts and methods forthe analysis of categorical data, and illustrate their usesand interpretations through examples.217