Hi, I wanted to follow up on this question as this is something near and dear to my heart - test-first design (TFD) and automated unit testing.  Philosophically, methodologies that take advantage of robust development processes are critical IMHO. Most SAS Programmers are not Developers - that is, most write their programs against the data, whereas Developers write their programs against requirements.  That distinction is very important in determining whether you (or your organization) have the support that you will need to utilize TFD.  The reason being is that this will require discipline and commitment to the approach. With that being said, I have included some references to our thinking on how you can/ should implement TFD in your SAS programming practices. FUTS - an open source framework for Unit Testing in SAS Using FUTS with Test First Design - SGF/ SUGI Paper Unit Testing Frameworks for SAS (Wiki) Robustness in SAS Applications (PhUSE Wiki) Hope this helps. -greg -greg ... View more

My apologies to all.  I have finally figured this out and realize many of you were giving me the right answer all along but I didn't know enough to recognize it.  As was pointed out (repeatedly) procedure codes go in the procedure field, diagnosis codes in the diagnosis field.  I assumed all ICD-9 codes appeared in the same field.  Rather, my diagnosis field can only hold ICD-9 diagnosis codes.  My procedure field can contain ICD-9 procedure codes, CPT codes, or HCPCS codes.  I have an additional variable which refers to which type of code is being used in the procedure field.  Because CPT and HCPCS codes always have 5 digits and ICD-9 procedure codes always have four, the additional indicator variable isn't even required to differentiate between the two. Thanks to everyone who was willing to bear with me on this one.  You guys are amazing. ... View more