Department of: Biostatistics and Epidemiology

Overview of SAS 6.12

SASHome Overview SAS is a large comprehensive statistical program for managing and analyzing data. We provide a brief overview of the program with focus on personal computer use. The program is often used by writing "batch" programs consisting of a set of commands, which we emphasize here. More extensive information can be found on the SAS home page. See statistical computing basics for a more general introduction. Access to the SAS software. It is possible to obtain a copy of SAS for your personal computer at Umass. The software is also available in University Public Computer Labs. To learn to use SAS, you need the software on your personal computer, and WEB access. The SAS Environment Starting the SAS program opens three windows: a. the Program Window used to write batch programs b. the Log Window- used to identify errors in programs, and review statistical processing c. the Output Window- used to view the results of the statistical procedures. These Windows can be viewed by CASCADE from the pull down WINDOW menu. You can move from one window to another by clicking on the mouse button while pointing in a Window. Using BATCH programs in SAS A sequence of SAS statements is a BATCH programs. The SAS statements are written in (or copied to) the PROGRAM window. When executed, they specify instructions to the SAS program. The WEB pages are designed to help learn how to use SAS with BATCH programs. We will copy into the SAS PROGRAM window existing SAS BATCH programs, and then run them. These programs are templates that can be modified for different data sets. Each program will have a similar structure. The programs are modular. The two types of modules are Data Steps and Procedures. As your knowledge of SAS increases, you will gain confidence to modify the programs for different applications. A typical SAS session will consist of : a. Copy into the SAS PROGRAM window a batch program. b. Modify the program. c. Run the program, check for errors, and debug it. d. Re-run the program until no errors occur. e. Save a copy of the new batch program f. Copy the results from the OUTPUT window in SAS to a word processor. g. Save the results in a word processor, and print a paper copy of them. h. Copy the batch program and word processor file onto a floppy storage disk. SAS Programs SAS programs consist of a list of SAS statements. The statements are executed in sequence. At the end of each statement is a semi-colon. The semi-colon is necessary for SAS to recognize the end of the statement and process it properly. A SAS statement is made up of key words (that the SAS program processes) and values (that you enter). We use UPPER case letters for SAS keywords to help emphasize their use, and lower case letters for values that the user has specified. Learning to Use SAS The Statistical Analysis System is a comprehensive software package. It is easy to become overwhelmed by the variety of options and possibilities. The WEB pages are organized to enable use of SAS for problem solving. Each page is limited in scope, but provides a template for accomplishing an objective. As your knowledge of SAS increases, you may accomplish multiple objectives in a single SAS program. This is the essence of the modular SAS language. Short courses on learning SAS are offered at Umass, and by SAS.