Hello fellow SAS users I have been working on the problem below over the past few days with very little success, and would very much appreciate your help here. Attach is a sample dataset in Excel that illustrates the data structure and what I want to achieve. Variable 'StudentID' is self-explanatory, indicating unique individuals. Variable 'Year' shows the yearly follow-up, in chronological order. Here, you can see that the duration of follow-up varies for each individual (between 3 and 7 years). In the real dataset I am working on, this varies from 2 to 10 years. Variable 'RuralPrac52w' indicates the event of interest in that year (1 for Yes, 0 for No). The final variable 'CorrEventCount' is what I wish to obtain from my coding (and I have not got there yet - which is why I am here). The logic/rule to create this final variable is quite simple, in plain English. It is similar to the counting process for repeated events in survival analysis. It goes like this: Within each unique StudentID, if RuralPrac52w=1 then it is 1 count for an event, whether this is for that particular year/row only, or for however many consecutive years. If there is a break in the event series (ie with a 0 in between), the counting will continue to the next event when another 1 occurs. Ultimately, Person 1 has 1 event of a continuous 2-year duration. Person 2 has 2 events, each of 1 year duration. Person 3 has 1 event of 3-year duration. Person 4 has 3 events (1st lasting 2 years, 2nd & 3rd 1 year each). Person 5 has 1 event of 5-year duration. My two main challenges are: (i) the changeable/unfixed durations of the event within-ID and of the follow-up period between-ID; and (ii) how to continue/resume the counting once the series is interrupted (ie from 1 to 0, or 0 to 1), and keep this process going until the last record for that person. Below is one of my recent (unsuccessful) syntax versions. data manyevents_count; set manyevents; by StudentID; retain countEvent; do i = 1 to last.StudentID; *set base value: 0 or 1 as approp; countEvent=RuralPrac52w; if RuralPrac52w=1 AND lag(lag(RuralPrac52w))=1 then countEvent=1; if RuralPrac52w=1 AND lag(lag(RuralPrac52w))=0 then countEvent=1; if RuralPrac52w=0 AND lag(lag(RuralPrac52w))=0 then countEvent=0; if RuralPrac52w=0 AND lag(lag(RuralPrac52w))=1 then countEvent=1; end; run; Look forward to any help or advice.
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