When I read the way that this user is working with SAS, I took a look around support.sas.com to find examples to allow you to work with your own data. (Take a look at this.) If this example isn't quite right for you, plug in your own key words.

Also, keep an eye on The Do Loop blog by Rick Wicklin, principal developer of PROC IML and SAS/IML Studio. (Rick is author of the book Statistical Programming with SAS/IML Software.)

Let me know what other papers, SAS Samples and examples you find that help you analyze prevalence  data. Have you developed your own analysis techniques? What are you doing with the data after analysis?