I have data on a year long program and need to count the number of sessions that occurred between certain number of months in the program. Cohorts in the program can start at any time in the year, and the timing of sessions is not prescribed; for example, session 18 might occur in month 7 for one cohort, but month 8 for another cohort. Participants might also miss sessions. In my data, each observation is a participant; I have the start date for each participant, and the dates of each session attended. How can I program the data step to count how many sessions a participant attended between months 1-6, 7-9, and 10-12? Existing variables: FirstSessionDate= date of first session attended Date_S1= date of session 1 Date_S2= date of session 2 ... (etc.) Date_S30= date of session 30 Variables I want: TS_1= number of sessions attended during months 1-6 TS_2=number of sessions attended during months 7-9 TS_3=number of sessions attended during months 10-12 Some example code I use for counting sessions in general (note, I edited this down, there are a lot of other things between this and surrounding it but they don't pertain to this question): data want;
set have;
ts=0; *TS: total number of sessions attended;
do number=1 to 30;
if &date_s1 ne "" then ts=ts+1;
end;
run;
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