Longitudinal Data and SAS

4   Flags and Counters

Introduction

Using a Flag Variable to Determine If a Particular Event Ever Occurred in Any One of Several Observations for Each Subject

Counting the Number of Positive Outcomes for Each Patient

Introduction

This is a fairly strange chapter name. Sure, you know what counters are, but what do flags have to do with SAS programming? The term “flag” is an old programming term for a variable that keeps track of things. For example, if a patient comes into the clinic on several occasions and you want to keep track if he or she ever had a particular medical problem, you could assign a flag to that task. You could turn it on (typically by setting it equal to 1) if the problem ever occurred and leave it off (typically by setting ...