topic Re: Date format sas in SAS Programming

Date format sas

mariamon0 — Wed, 22 Apr 2020 11:31:43 GMT

I'm trying to calculate age based on the date they came for a visit (date0) and their date of birth (dob0)

aget=(date0)-(dob0)/365.25;

this calculated age is not working. Do I need to formate anything?

Re: Date format sas

ed_sas_member — Wed, 22 Apr 2020 11:33:12 GMT

Hi @mariamon0

Could you please provide some sample data and specify variable types (character / numeric ) ?

best,

Re: Date format sas

Jagadishkatam — Wed, 22 Apr 2020 11:33:58 GMT

This code should work, unless there is no issue with the date0 or dob0 variables. Could you please check if the date variables are numeric, please post the sample data to understand the query and help you better.

Re: Date format sas

mariamon0 — Wed, 22 Apr 2020 11:39:10 GMT

The date variables are in date format:

visit date: 1/25/2016

date of birth: 2/17/1940

how do I change the format?

Re: Date format sas

PaigeMiller — Wed, 22 Apr 2020 11:40:50 GMT

@mariamon0 wrote:

I'm trying to calculate age based on the date they came for a visit (date0) and their date of birth (dob0)

aget=(date0)-(dob0)/365.25;

this calculated age is not working. Do I need to formate anything?

Formatting doesn't change the math. It only changes the appearance of a number. Also, to compute age you can use the INTCK function or the YRDIF function.

But really, you should tell us more than just "not working". You should show us the LOG (code plus warning and error messages, do not chop anything out), and a portion of your data. This will provide sufficient information so we can diagnose the problems. Saying "not working" tells us nothing.

Re: Date format sas

PaigeMiller — Wed, 22 Apr 2020 11:41:40 GMT

@mariamon0 wrote:

The date variables are in date format:

visit date: 1/25/2016

date of birth: 2/17/1940

how do I change the format?

Formatting doesn't change the math. Are these numeric, or character (text), according to PROC CONTENTS???

Re: Date format sas

mariamon0 — Wed, 22 Apr 2020 11:50:43 GMT

I'm not getting whole numbers when I do a proc print of aget. The log appears completely fine. Both date of birth and date visit are numeric variables

Re: Date format sas

PaigeMiller — Wed, 22 Apr 2020 12:01:16 GMT

Yes, your formula doesn't produce whole numbers.

If you use the INTCK() function or the YRDIF() function, you get whole numbers.

Re: Date format sas

mariamon0 — Wed, 22 Apr 2020 12:03:08 GMT

What would the code look like for that?

my date of birth variable is v_dob_0

and my visit date variable is v_date_0

Re: Date format sas

Jagadishkatam — Wed, 22 Apr 2020 12:08:44 GMT

you can try the below code

I assume that the variables are character, so converting them to numeric

data have;
input date0:mmddyy10. dob0:mmddyy10.;
aget=(date0-dob0)/365.25;
cards;
1/25/2016 2/17/1940
;

Re: Date format sas

PaigeMiller — Wed, 22 Apr 2020 12:16:44 GMT

@mariamon0 wrote:

What would the code look like for that?

my date of birth variable is v_dob_0

and my visit date variable is v_date_0

The documentation I linked to shows simple examples.

To correct an earlier statement I made, YRDIF does not return an integer. INTCK does return an integer.

Re: Date format sas

Astounding — Wed, 22 Apr 2020 13:16:19 GMT

@Jagadishkatam has given you the correct formula. The formula you originally used was incorrect:

aget=(date0)-(dob0)/365.25;

Using your formula, SAS would perform the division first, then the subtraction.

Re: Date format sas

ballardw — Wed, 22 Apr 2020 14:44:59 GMT

@mariamon0 wrote:

I'm not getting whole numbers when I do a proc print of aget. The log appears completely fine. Both date of birth and date visit are numeric variables

Please explain why with a formula like this you expected integers:

aget=(date0)-(dob0)/365.25;

Between 1 and 10000 days difference between two dates you will find exactly 6 values that would have an integer result. And that when the formula is:

aget=(date0 - dob0)/365.25;