Longitudinal data - cases with extra sessions

[hwangnyc]

I have longitudinal data that is in long form. The vast majority of my cases have 5 sessions. But there is a cases 8 sessions thus skewing things a bit and a case with 6. I’d like to be able to plot a timeline where the ending session is their last/final session. Here’s how I envision my data. Any suggestions or issues you think would occur with this would be greatly appreciated. Thanks!

ID	Session	Want
100	1	1
100	2	2
100	3	3
100	4	4
100	5	Last
101	1	1
101	2	2
101	3	3
101	4	4
101	5	Last
102	1	1
102	2	2
102	3	3
102	4	4
102	5	Last
103	1	1
103	2	2
103	3	3
103	4	4
103	5	5
103	6	6
103	7	7
103	8	Last
104	1	1
104	2	2
104	3	3
104	4	4
104	5	5
104	6	Last

[ballardw]

This will subset the data if sorted by id session:

data want;
   set have;
   by  id session;
   if session in (1,2,3,4) or Last.id;
run;

If you really want to add a variable as shown something like:

data want;
   set have;
   by  id session;
   length want $ 4.;
   if session in (1,2,3,4) then Want=put(session,best4.);
   else if last.id then Want='Last';
run;