Date:         Fri, 21 Apr 2006 12:25:46 -0700
Reply-To:     Dale McLerran <stringplayer_2@YAHOO.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Dale McLerran <stringplayer_2@YAHOO.COM>
Subject:      Re: power analysis: "one sample, one test"?
In-Reply-To:  <1145637199.364637.283440@i40g2000cwc.googlegroups.com>
Content-Type: text/plain; charset=iso-8859-1

--- jzawisa@GMAIL.COM wrote:

> Should sample size computations for power analysis be based on "one
> sample, one test".  That is, if I have two primary outcomes, and the
> necessary sample size for the first is N=300, and the necessary
> sample
> size for the second is 150, will I need to have a sample of 450, or
> 300, since such a sample would be adequately large for both tests.
>
> Thanks,
>
> John Zawisa
>

John,

You do not need to collect additional samples for each preplanned
hypothesis that you wish to test.  You only need the N=300 for
testing both hypotheses.

Dale


---------------------------------------
Dale McLerran
Fred Hutchinson Cancer Research Center
mailto: dmclerra@NO_SPAMfhcrc.org
Ph:  (206) 667-2926
Fax: (206) 667-5977
---------------------------------------

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