Calculate date from two dates proc sql

[Anita_n]

Dear all,

am a little bit confused about calculating age from two dates.

I have seen different methods and am not sure which is right.

Is it right to calculate age considering leap years:

 (in years this way): intck("year", birthdate, interviewdate)

(in months): intck("month", birthdate, interviewdate)

(in days): intck("day", birthdate, interviewdate)

Is it also right to use: floor((interviewdate-birthdate)/365)

thanks for the help

[PaigeMiller]

Dividing by 365 ignores leap years, and in some cases will result in incorrect ages.

INTCK is the better method and does take into account leap years

[Kurt_Bremser]

Also take a good look at the YRDIF function.

[andreas_lds]

A correct calculation requires using the fourth parameter of intck, because someone born on 1. April 2011 is still nine years old, not ten (for future readers: today is 03.02.2021 ddmmyy).

 69         data _null_;
 70            birthday = '01Apr2011'd;
 71            today = today(); /*'03Feb2021'd;*/
 72         
 73            yd = yrdif(birthday, today);
 74            d1 = intck('year', birthday, today);
 75            d2 = intck('year', birthday, today, 'c');
 76         
 77            put yd=;
 78            put d1=;
 79            put d2=;
 80         run;
 
 yd=9.8438356164
 d1=10
 d2=9

[Anita_n]

Thanks to you all for the reply. I now understand the principle behind it