Newsgroups: comp.soft-sys.stat.spss
Date: 2003-01-17 13:03:20 PST

In response to a discussion on this list a few years ago, I wrote the 
following syntax to compare 3 traditional ways to compute *age* at admission.
I recommend the second way.
I don't have the time at the moment to cut down the old syntax so I just 
added a few example cases using 1/1/2003 as the reference date.
I your application all cases would have the same "admission" date, so 
you could just put it in a compute.
compute admsndat= date.mdy(1,1,2003).
Hope this helps.

*Art
**Art*@DrKendall.org
Social Research Consultants
University Park, MD USA


new file.
* this program compares different ways of finding the *age*.
*note that cases 1, 2, and 6 have the same Gregorian month and day for 
birth and admission.
*but notice the julian day-within-the-year in variable jborn.
*make up some data.
data list list / birthdat(adate10)  admsndat(adate10) wanted (f3).
begin data.
    4/10/1931 4/10/2002 71
   4/10/1933 4/10/2002 69
   4/10/1932 4/7/2002   69
  4/10/1932 4/8/2002   69
  4/10/1932 4/9/2002   69
  4/10/1932 4/10/2002 70
  4/10/1932 4/11/2002 70
  4/10/1932 4/12/2002 70
  4/10/1932 4/13/2002 70
    1/1/2000   1/1/2003 3
    1/1/2001   1/1/2003 2
    1/1/2002   1/1/2003 1
    12/31/2002 1/1/2003 0
    1/2/1933   1/1/2003 69
    1/1/1933   1/1/2003 70

end data.
numeric age1 age2 age3 (f3).
*method 1.
COMPUTE age1 = trunc(CTIME.DAYS(admsndat - birthdat)  / 365.25) .
* method2  see if birthday in current year has occurred yet.
compute bmo = xdate.month(birthdat).
compute bdom = xdate.mday(birthdat).
compute byr =   xdate.year(birthdat).
compute amo = xdate.month(admsndat).
compute adom = xdate.mday(admsndat).
compute ayr =   xdate.year(admsndat).
compute nearbirt = date.mdy(bmo,bdom,ayr).
do if nearbirt le admsndat.
compute age2 = ayr-byr.
else if nearbirt gt admsndat.
compute age2 = ayr-byr-1.
end if.
formats nearbirt (adate10) age2 (f3).
* method 3  jdate way from earlier responder.
compute age3 = xdate.year(admsndat) - xdate.year(birthdat)
               - ( xdate.jdate(birthdat) > xdate.jdate(admsndat) ).
compute age3 = xdate.year(admsndat) - xdate.year(birthdat)
               - ( xdate.jdate(birthdat) gt xdate.jdate(admsndat) ).
compute jadm = xdate.jdate(admsndat) .
compute jborn = xdate.jdate(birthdat) .
formats age3 jborn jadm(f3).
numeric line (f2).
compute case = $casenum.
list /variables = case admsndat birthdat wanted age1 age2 age3  jborn jadm.


Susan T wrote:
> Hi!  I'm using SPSS 10.1 Win, and have a quick question
> that I've been stuck on today.  I have a data file that
> includes birthdates in Date format (dd-mmm-yyyy).
> I want to calculate an *age* for each person as of
> January 1, 2003.
> 
> Can someone help me?  Thanks!
> 
> Susan
> 
>