topic Difference between dates across rows in SAS Programming

Difference between dates across rows

Cruise — Tue, 03 Jul 2018 18:49:36 GMT

Hi guys, I thought below would manage calculating the difference between time periods across each rows. But I wind up with not only huge but negative numbers. Please help correcting this syntax out. What I want is about 132 days difference between two rows (07022002 and 11142002) in the second row instead 4120000 and so forth so on for the rest of the rows.

Thanks a lot in advance.

data diff_date;
input Date_Visit $ ID $;
cards;
07022002 83
11142002 83
05152003 83
11042003 83
05042004 83
11102004 83
05032005 83
11012005 83
06062006 83
;

data b; set diff_date;  
/*format date_visit 9.;*/
by child_id;
retain r_date;
r_date=lag(date_visit);
if not first.child_id then do;
diff_visit=date_visit-r_date;
end;
drop r_:;
run;

Re: Difference between dates across rows

Kurt_Bremser — Tue, 03 Jul 2018 18:59:25 GMT

11142002 is not a date, but a 8-digit number (by now - more than 300 posts here - you should know that). Store dates as SAS date values, and use intck() to get distances in time.

Re: Difference between dates across rows

Astounding — Tue, 03 Jul 2018 19:14:14 GMT

It would take a few changes here and there, starting with how you read in the data.

data diff_date;
input Date_Visit mmddyy8.  ID $;
cards;
07022002 83
11142002 83
05152003 83
11042003 83
05042004 83
11102004 83
05032005 83
11012005 83
06062006 83
;

data want; 
set diff_date;  
by id;
diff_visit = dif(date_visit);
if first.id then diff_visit = .;
run;