Survival Analysis Using SAS®: A Practical Guide

Data Structure

The LIFETEST, LIFEREG, and PHREG procedures all expect data with the same basic structure. Indeed, this structure is fairly standard across many different computer packages for survival analysis. For each case in the sample, there must be one variable (which I’ll call DUR) that contains either the time that an event occurred or, for censored cases, the last time at which that case was observed, both measured from the chosen origin. A second variable (which I’ll call STATUS) is necessary if some of the cases are censored or if you want to distinguish different kinds of events. The variable STATUS is assigned arbitrary values that indicate the status of the individual at the time recorded in the DUR variable. If there is only one ...