Art,

No, logically irrational. I think most of the problems with the SAS language come from lack of communication between developers in different parts of the system and the failure of documenters to explain the significance of features.

Perhaps, it was easy to implement LAG as value from last observation because of the simplicity of the way SPSS reads data. Personally, I much prefer a general tool, and having many ways of bringing data into the DATA step. Perhaps it is my background in mathematics showing, but I have always preferred general use tools to tools for specific problems.

I never found it difficult to understand that LAG returned the last value put in, and the consequence that you could not obtain the value from the last record when you didn't put a value from the last record in. Since LAG has been around for at least 25 years and probably much more, I would like to see someone give an accurate verifiable history of the introduction of SPSS LAG and SAS LAG into their respective systems.

I haven't looked at the SPSS recode procedure in many years. Perhaps you could explain its superiority in a way that would not be trivial to implement in SAS.

How does REORDER differ from PROC SORT? Is it a feature of having all data present in memory at once?

Ian Whitlock =============== Date: Fri, 28 Oct 2005 09:13:37 -0400 Reply-To: Arthur Tabachneck <art297@NETSCAPE.NET> Sender: "SAS(r) Discussion" From: Arthur Tabachneck <art297@NETSCAPE.NET> Subject: Re: Lag function Comments: To: sas-l Peter, Whether they were naïve or not aside, SPSS did come up with at least three commands that I only wish SAS would eventually duplicate: lag, recode and reorder. Yes, SAS does have alternative means for solving the same problems, ways which provide even more versatility and control, but not ways that seem logically intuitve. Does that mean that SAS is illogically irrational? Art <snip>