Introduction If you took the lesson , you learned how to read data, perform basic modifications, and create a new SAS data set. This lesson teaches you what happens "behind the scenes" when the DATA step reads raw data. You'll examine the program data vector, which is a logical framework that SAS uses when creating SAS data sets.

Understanding how the program operates can help you to anticipate how variables will be created and processed, to plan your modifications, and to interpret and debug program errors. It also gives you useful strategies for preventing and correcting common DATA step errors.

Time to Complete This lesson contains pages and takes approximately 1.5 hours to complete.

Objectives In this lesson, you learn to identify the two phases that occur when a DATA step is processed interpret automatic variables identify the processing phase in which an error occurs debug SAS DATA steps test programs by limiting the number of observations that are created flag errors in the SAS log.

Prerequisites Before taking this lesson, you should complete the following lessons: .