Hi! I need help calculating the number of actual days a person was in my 5 year study. So, looking accross observations, I need to calculate number of days between the first encounter date 'encdate' and last encounter date by 'patientid'.
Assistance is apprecited!
Here's one approach.
proc summary data=have nway;
class patientid;
var encdate;
output out=durations (keep=patientid firstday lastday) min=firstday max=lastday;
run;
This gives you a data set with three variables in it, and one observation per patientid. You can use that in a DATA step, and apply whichever formula you wish:
duration = lastday - firstday;
duration = lastday - firstday + 1;
The SQL programmers out there can do this in one step, but SQL isn't my strong point.
Please post sample input and output data.
Here's one approach.
proc summary data=have nway;
class patientid;
var encdate;
output out=durations (keep=patientid firstday lastday) min=firstday max=lastday;
run;
This gives you a data set with three variables in it, and one observation per patientid. You can use that in a DATA step, and apply whichever formula you wish:
duration = lastday - firstday;
duration = lastday - firstday + 1;
The SQL programmers out there can do this in one step, but SQL isn't my strong point.
Minor change to @Astounding solution:
output out=durations (keep=patientid firstday lastday) range=;
Range will basically do the max-min.
how can i get sas software
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Or use SAS Academics on Demand -> Independent Learners option.
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