A Programmer’s Guide

**Author:** Ron Cody

**Publisher:** SAS Publishing

SAS makes it easy to work with the data of a single observation and with
summary data that combines the information of a group of observations.
Sometimes, though, it is necessary to do computations that draw values from
more than one observation — not simply as summary data, but combining the
detail data of multiple observations. *Longitudinal Data and SAS* is a book of
programming techniques for these situations, from simple BY group processing
to transposing.

POSTED BY
GLOBAL STATEMENTS BOOKS
ON SEPTEMBER 19, 2007

**Year:** 2001

**ISBN:** 1-58025-924-3

**Pages:** 174

**Publisher’s list price:** 32.95

- 1. The RETAIN Statement
- 2. The LAG and DIF Functions
- 3. FIRST. and LAST. Temporary Variables
- 4. Flags and Counters
- 5. Summarizing Data Using PROC MEANS and PROC FREQ
- 6. Using PROC SQL with Longitudinal Data
- 7. Restructuring SAS Data Sets Using Arrays
- 8. Restructuring SAS Data Sets Using PROC TRANSPOSE
- 9. Study One: Operations on a Clinical Database
- 10. Study Two: Operations on Daily Weather Data and Ozone Levels
- 11. Study Three: Producing Summary Reports on a Library Data Set
- 12. Useful Macros
- Appendix. List of Data Files and SAS Data Sets
- Index

Working with longitudinal data introduces a unique set of challenges. Once you’ve mastered the art of performing calculations within a single observation of a data set, you’re faced with the task of performing calculations or making comparisons between observations.

It is simple to look backward in data sets, but how do you look forward and across observations? Ron Cody provides straightforward answers to these and other questions.

UPDATED BY
GLOBAL STATEMENTS BOOKS
ON APRIL 2, 2007