topic Re: number of days in the study period in SAS Programming

number of days in the study period

jenim514 — Thu, 02 Jun 2016 18:12:29 GMT

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!

Re: number of days in the study period

Reeza — Thu, 02 Jun 2016 18:26:08 GMT

Please post sample input and output data.

Re: number of days in the study period

Astounding — Thu, 02 Jun 2016 18:31:25 GMT

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.

Re: number of days in the study period

ballardw — Thu, 02 Jun 2016 19:31:40 GMT

Minor change to @Astounding solution:

output out=durations (keep=patientid firstday lastday) range=;

Range will basically do the max-min.

Re: number of days in the study period

kvemulapalli571 — Thu, 02 Jun 2016 20:16:59 GMT

how can i get sas software

Re: number of days in the study period

kvemulapalli571 — Thu, 02 Jun 2016 20:21:49 GMT

please help me how can i get sas software

Re: number of days in the study period

Reeza — Thu, 02 Jun 2016 22:38:41 GMT

@kvemulapalli571

1. Please post your questions in a new discussion rather than in someone else's question

2. Google "SAS University Edition" -> This is a free version of SAS available for learning purposes only. You need a 64bit machine.

Or use SAS Academics on Demand -> Independent Learners option.