Date:         Fri, 21 Sep 2007 11:31:07 -0700
Reply-To:     "Pardee, Roy" <pardee.r@GHC.ORG>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Pardee, Roy" <pardee.r@GHC.ORG>
Subject:      Re: How to randomly divide sample in 2 groups
In-Reply-To:  A<200709211752.l8LGBvqM018637@mailgw.cc.uga.edu>
Content-Type: text/plain; charset="US-ASCII"

No doubt there are fancier ways, but something like this should work:

Data have ;
  set have ;
  randy = uniform(123456) ;
Run ;

Proc sort data = have ;
  by randy ;
Run ;

Data want ;
  set have ;
  if _n_ le 200 then condition = 'control' ;
  else condition = 'case' ;
Run ;

Proc freq data = want ;
  tables condition / missing ;
Run ;

HTH

-Roy

-----Original Message-----
From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of
Sophia Tong
Sent: Friday, September 21, 2007 10:53 AM
To: SAS-L@LISTSERV.UGA.EDU
Subject: How to randomly divide sample in 2 groups

Dear all,
 I have 400 people in a pool, want to randomly assign them into 2
groups, 200 each without any restrictions. What's right way of doing it?

I have tried somthing like

DATA want;
  SET have;
  SEED=339487731;
  R=RANUNI(SEED);
  R2=ROUND(1+R);
  RUN;

But the R2 won't give me 200/200. Please help.

Thanks,

Sophia