Date:         Wed, 31 Mar 2010 10:11:59 -0700
Reply-To:     Tan <tan.p.pham@GMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Tan <tan.p.pham@GMAIL.COM>
Organization: http://groups.google.com
Subject:      SAS and dates
Comments: To: sas-l@uga.edu
Content-Type: text/plain; charset=ISO-8859-1

I'm an Masters level student working on my thesis. I am trying to
figure out how to do this.

So basically I want to know how long has a person been living with a
disease on the day he/she took the survey. So I have the date that the
person has been diagnosed with a disease and the date the person took
the survey.
both dates are in datetime22.3 format and informat.

I know SAS keeps dates by the number of days since (or before) a
certain date.

So I figure to find out my question I would do:

LengthDisease=datesurveytaken-datediseasedx;

I figure that would give me days and i want this in years, so I would
do:

LengthDisease1=LengthDisease/365;

I get really odd results.

For my first case i get LengthDisease=34883200 and
LengthDisease1=68173.

I think my logic on getting this data makes sense. But clearly a 31
year old person would not have the disease for 68173 years.  So I am
unsure what i am doing wrong to get this data... I am hoping someone
on this message board can help.