You should use the INTCK function to calculate the difference between to dates.

Gadi

-----Original Message----- From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of pritesh Sent: Saturday, December 06, 2008 5:01 PM To: SAS-L@LISTSERV.UGA.EDU Subject: Re: SAS Negative Date Values

On Dec 5, 6:54 pm, Virtual SUG <sfbay0...@aol.com> wrote: > On Dec 5, 6:10 pm, pritesh <priteshka...@gmail.com> wrote: > > > I have a slight problem. I am trying to create an age variable for my > > dataset. The problem I am having is that some patients were born in > > 1920s or 1930s and therefore when I create an age variable, it is > > negative in some cases. Is there a way for me to convert these > > negative values to positive values so that I don't have a negative age > > value (when I divide by 365) for patients? Thanks :) > > I think there's a misunderstanding here about how SAS stores the > values of date variables in your data sets. > > A SAS date variable is the number of days before or after Jan 1, > 1960. If, in your case, the patient was born on 1/1/1960, then their > SAS date value is zero (0). If they were born after 1/1/1960, their > birthday is stored as a positive integer, and if they were born BEFORE > 1/1/1960, then their date value is a negative integer. > > I am not sure why you want to divide a SAS date variable's value > representing someone's birthday by any value, much less 365. What is > it that you are trying to accomplish? If you want to determine > someone's age, you also need a starting point for the calculation, > such as today, or yesterday, or some other "reference point." > > Please reply back to the list and clarify what it is your are trying > to do. Also, you may want to read the SAS Language Reference: > Concepts manual's chapter on SAS date/time handling. You can also > download a PDF, at no charge, or my presentation, "Working with SAS > Date and Time Functions," from the "user group presentations" link athttp://www.sierrainformation.com > > Hope this helps. > > Andrew Karp > Sierra Information Serviceswww.SierraInformation.com

Sorry for not being clear earlier. I am trying to find out the age of study participants from the day they were interviewed. So I used the following code:

data work.alldata5; set work.alldata4; dob1=input(dob,mmddyy6.); intdate1=input(intdate,mmddyy6.); age=(intdate1-dob1)/365.25; ageround=FLOOR(age); run;

So the problem is that when I try to get age values for those born before 1960, they will show up as negative values. Is there any way I can rectify this? Thanks