RE: st: RE: power calculation in a case control design

["Newson, Roger B" <r.newson@imperial.ac.uk>]

Power calculations for case-control studies are discussed in Newson
(2004), which you can download in pre-publication draft form from my
website (see below). The program used is -powercal-, downloadable from
SSC using the -ssc- command in Stata, which is a unified tool for a
variety of power calculations.

I hope this helps.

Best wishes

Roger

References

Newson R. Generalized power calculations for generalized linear models
and more. The Stata Journal 2004; 4(4): 379-401. Download
pre-publication draft from 
www.imperial.ac.uk/nhli/r.newson/


Roger Newson
Lecturer in Medical Statistics
Respiratory Epidemiology and Public Health Group
National Heart and Lung Institute
Imperial College London
Royal Brompton campus
Room 33, Emmanuel Kaye Building
1B Manresa Road
London SW3 6LR
UNITED KINGDOM
Tel: +44 (0)20 7352 8121 ext 3381
Fax: +44 (0)20 7351 8322
Email: r.newson@imperial.ac.uk 
www.imperial.ac.uk/nhli/r.newson/

Opinions expressed are those of the author, not of the institution.

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of stata_user
stata_user
Sent: 30 January 2007 21:41
To: statalist@hsphsun2.harvard.edu
Subject: RE: st: RE: power calculation in a case control design

Thanks a lot for all the suggestions and help.

I could not answer the emails earlier, sorry about that.

The prevalence of exposure in the control group is

19 or 13%

It is a difficult situation compared to the situation where we have to
test 
equal means or equal proportions

I will appreciate any further suggestions

Sami


>From: "Visintainer, Paul" <PAUL_VISINTAINER@NYMC.EDU>
>Reply-To: statalist@hsphsun2.harvard.edu
>To: <statalist@hsphsun2.harvard.edu>
>Subject: st: RE: power calculation in a case control design
>Date: Tue, 30 Jan 2007 11:06:45 -0500
>
>What's the (assumed) prevalence of exposure in your control group?
>
>______________________________________
>Paul F. Visintainer, PhD
>Professor and Chair
>Department of Epidemiology and Biostatistics
>School of Public Health
>New York Medical College
>PH: (914) 594-4804
>FX: (914) 594-4853
>
>-----Original Message-----
>From: owner-statalist@hsphsun2.harvard.edu
>[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of stata_user
>stata_user
>Sent: Friday, January 26, 2007 4:58 PM
>To: statalist@hsphsun2.harvard.edu
>Subject: st: power calculation in a case control design
>
>Dear All,
>
>
>
>I have a case control design with 83 cases and 139 controls.
>
>   I am intersted  in the power of two sided 5% (or 1 sided) test to
>detect
>an approximate relative risk of less than 4.
>
>Is there any possibility to have a solution using  stata?
>
>Thanks a lot
>Sami
>
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