Date:         Thu, 6 Sep 2007 08:53:24 -0500
Reply-To:     Mary <mlhoward@avalon.net>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Mary <mlhoward@AVALON.NET>
Subject:      Re: Question: Creating ratios using a DO loop
Content-Type: text/plain; charset="iso-8859-1"

Hi, Andy,

I don't think that you need a do loop.

I would form a new column in the data that is the number of days from today's date, then this would have a number in it, 0, 1, 2, 3, etc.  You would subtract the date on each record from today's date to get it; say we call it dayscount.

Then you can use SQL with a where clause:

Create table tablename
   select  id, {calculation} as newvarname
   where dayscount > 2;

-Mary
  ----- Original Message ----- 
  From: andymanme@GOOGLEMAIL.COM 
  To: SAS-L@LISTSERV.UGA.EDU 
  Sent: Thursday, September 06, 2007 7:58 AM
  Subject: Question: Creating ratios using a DO loop


  Hi everyone,

  Hope someone can help, I have a data set:

  data input;
          format Date ddmmyy10.;
          input Date ddmmyy10. ID $ Var;
  datalines;
  01/01/1980 A 6
  05/01/1980 A 10
  06/01/1980 A 4
  07/01/1980 A 2
  08/01/1980 A 10
  12/01/1980 A 4
  03/01/1980 B 2
  09/01/1980 B 4
  12/01/1980 B 6
  ;
  run;

  Using which I want to create an Average of the variable Var, the
  complication comes from me wishing to only use the observations per ID
  which are 2 days or more in the past.  So for example I would wish the
  output to look like:


  data required;
          format Date ddmmyy10.;
          input Date ddmmyy10. ID $ Var Avg;
  datalines;
  01/01/1980 A 6 .
  05/01/1980 A 10 6
  06/01/1980 A 4 6
  07/01/1980 A 2 8
  08/01/1980 A 10 10
  12/01/1980 A 4 6.4
  03/01/1980 B 2 .
  09/01/1980 B 4 2
  12/01/1980 B 6 3
  ;
  run;

  So you can see that for ID A on 08/01/1980 we are using the
  observations from 01/01/1980, 05/01/1980 and 06/01/1980.  We do not
  use the observation from 07/01/1980 as that was only 1 day prior to
  08/01/1980.  But when we come to calculate the average for the
  12/01/1980 we are using all of the prior observations for that ID (A).

  I suspect I need to use some form of DO loop to go through the data,
  but I am unsure as to how to code this up.

  Hopefully someone can help!?
  Andy