Cody's Data Cleaning Techniques Using SAS, Second Edition

5 Looking for Duplicates and "n" Observations per Subject

Introduction

Eliminating Duplicates by Using PROC SORT

Detecting Duplicates by Using DATA Step Approaches

Using PROC FREQ to Detect Duplicate ID’s

Selecting Patients with Duplicate Observations by Using a Macro List and SQL

Identifying Subjects with "n" Observations Each (DATA Step Approach)

Identifying Subjects with "n" Observations Each (Using PROC FREQ)

Introduction

Besides checking for invalid data values in a data set, it may be necessary to check for either duplicate ID’s or duplicate observations. Duplicate observations are easy to fix; just eliminate the duplicates (although you may want to find out how the duplicates got there). Duplicate ID’s with different data values present ...