topic Re: Calculate duration when there are multiple dates in SAS Data Management

Calculate duration when there are multiple dates

batulelec — Mon, 06 Jun 2016 21:35:42 GMT

How do I calculate duration when I have multiple dates.

For example -

Peson ID Diagnosis Date1 Date2 Date3......Date50

I want to be able to calculate the difference between Date50 and Date49, Date49 and Date 48 and so on. Is wide data the way to go for this estimation or should my data be vertical instead?

Thank you!

Re: Calculate duration when there are multiple dates

ballardw — Mon, 06 Jun 2016 22:10:47 GMT

The first thing is to have the dates as SAS date values, are they?

What the intervals will be used for would likely determine the final format.

If the data is currently in wide form with the values as SAS dates then:

data want;

set have;

array dates date1-date50;

array dur duration1-duration-50;

do i = 1 to (dim (dates) - 1);

duration[i+1] = dates[i+1] - dates[i];

end;

run;

duration would be in days. duration1 is basically a place holder to keep the references easy to manage.

Re: Calculate duration when there are multiple dates

PGStats — Mon, 06 Jun 2016 22:36:41 GMT

If you want to go to a long (vertical) data structure and calculate durations :

data want;
set have;
array _d date1-date50;
do i = 1 to dim(_d);
	date = _d{i};
	if not missing(date) then do;
		call missing(duration);
		if i > 1 then if not missing(_d{i-1}) then 
			duration = intck("DAY", _d{i-1}, date);
		output;
		end;
	end;
drop i date1-date50;
run;

Re: Calculate duration when there are multiple dates

Astounding — Tue, 07 Jun 2016 00:03:29 GMT

Remember, if you have 50 days you have only 49 durations.

Re: Calculate duration when there are multiple dates

batulelec — Tue, 07 Jun 2016 14:45:57 GMT

Thank you, this works!

Re: Calculate duration when there are multiple dates

batulelec — Tue, 07 Jun 2016 14:50:56 GMT

Yes, you are correct - thank you!

Re: Calculate duration when there are multiple dates

batulelec — Tue, 07 Jun 2016 14:51:50 GMT

Thank you!

Re: Calculate duration when there are multiple dates

lauralawton — Tue, 07 Jun 2016 16:13:34 GMT

Hello batulelec,

Welcome to the SAS Data Management Community. I'm glad you found some useful info! If one of the replies was the exact solution to your problem, can you "Accept it as a solution"? Or if one was particularly helpful, feel free to "Like" it. This will help other community members who may run into the same issue know what worked.

Thanks!

Laura