Longitudinal Data and SAS

9   Study One: Operations on a Clinical Database

Study One: Operations on a Clinical Database

Introduction

Description of the Clinical Data Set

Selecting the First or Last Visit for Each Patient

Computing Differences between the First and Last Visits

Another Method of Computing Differences between the First and Last Visits

Computing Differences between Every Visit

Counting the Number of Visits for Each Patient (DATA Step Approach)

Counting the Number of Visits for Each Patient (PROC FREQ)

Counting the Number of Visits for Each Patient (PROC MEANS)

Counting the Number of Visits for Each Patient (PROC SQL)

Selecting All Patients with n Visits (DATA Step Approach)

Selecting All Patients with n Visits (PROC FREQ Approach)

Selecting All Patients with ...