Longitudinal Data and SAS

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.


Paperback (2001–SAS 8)


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

From the back cover

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.