Date:         Mon, 20 Dec 1999 03:34:29 GMT
Reply-To:     SAlbert <salbert@AOL.COMSTOPSPAM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         SAlbert <salbert@AOL.COMSTOPSPAM>
Organization: AOL http://www.aol.com
Subject:      Re: random sampling

 Ju-Tsung Pi wrote:>
>         I have a data set of 887 observations from a normal distribution. I
>would like to draw a
>         sample of 250 observations out ot 887 obs. How can I do this?
>         Thanks!
>

If you only need approximately 250, you can use code like the following:

data two;
   set one(where=(ranuni(0) < 250.0/887));
run;

If you need an exact 250, you could try several approaches, but the easiest
would be to add a random variable, sort on it, and then take the first 250
cases:
data two;
  set one;
  dummy = ranuni(0);
run;
proc sort data=two;
  by dummy;
run;
data three;
  set two(obs=250);
run;

Note:  code above has not been tested.

Steve Albert