Categorical Data Analysis Using The SAS® System, 2nd Edition

17.1. Introduction

Categorical data often are generated from studies that have time from treatment or exposure until some event as their outcome. Such data are known as time-to-event data. The event may be death, the recurrence of some condition, or the emergence of a developmental characteristic. Often, the outcome is the actual lifetime (or waiting time), which is the response analyzed in typical survival analyses. However, due to resource constraints or the need to perform a diagnostic procedure, you sometimes can determine only the interval of time during which an event occurs. Examples include examining dental patients for caries at six-month periods, evaluating animals every four hours after their exposure to bacteria, and examining patients ...