SAS Certification Prep Guide, 4th Edition

Reading and Writing Only Essential Data

Overview

Best practices specify that you should write programs that read and write only essential data. If you process fewer observations and variables, you conserve resources. This topic covers many different techniques that can improve performance.

Selecting Observations Using Subsetting IF versus WHERE Statement

You can use WHERE statements or subsetting IF statements to subset data. Although both statements test a condition to determine whether SAS should select an observation, the WHERE statement is more efficient.

The following graphic illustrates differences between these statements.

I/O