Solved: computing age in years from SAS dates

Banke · Posted 10-28-2022 07:15 PM

Hello everyone,

I have two variables: start_year and end_year. start_year is in recorded in years and in format numeric 8. while end_year is mmddyy10.

i have tried to subtract and get the age but i keep getting funny values even with some of the codes i found.

Attached is the simplest code i tried, your help is highly appreciated.

sample data.

start_date (8.) end_date(mmddyy10.)

2015 01/02/2017

2013 05/07/2014

2018 06/06/2019

data want;
set have;
format end_date year4.;
end_date2  = end_date;
format end_date2 8.;
age = end_date2 - start_date;
run;

mkeintz · Posted 10-28-2022 07:23 PM

The calculation

age = end_date2 - start_date;

would generate the same result no matter what format you apply to the end_date2 and start_date variables.

You need a function to extract the YEAR component of the end_date value (which is numerically the number of days after 01jan1960). So use

data want;
  set have;
  age = year(end_date) - start_date;
run;

Of course, this will return the same value for the entire 365 (or 366) days that END_DATE might have over the course of a single calendar year.

--------------------------
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mkeintz · Posted 10-28-2022 07:23 PM

The calculation

age = end_date2 - start_date;

would generate the same result no matter what format you apply to the end_date2 and start_date variables.

You need a function to extract the YEAR component of the end_date value (which is numerically the number of days after 01jan1960). So use

data want;
  set have;
  age = year(end_date) - start_date;
run;

Of course, this will return the same value for the entire 365 (or 366) days that END_DATE might have over the course of a single calendar year.

--------------------------
The hash OUTPUT method will overwrite a SAS data set, but not append. That can be costly. Consider voting for Add a HASH object method which would append a hash object to an existing SAS data set

Would enabling PROC SORT to simultaneously output multiple datasets be useful? Then vote for
Allow PROC SORT to output multiple datasets

--------------------------

Banke · Posted 10-28-2022 07:31 PM

Thank you so much!

computing age in years from SAS dates