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st: Re: RE: CASE-CONTROL STUDY


From   "Ishay Barat" <i.b@dadlnet.dk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: Re: RE: CASE-CONTROL STUDY
Date   Sun, 15 Mar 2009 17:52:17 +0100

Dear Kieran and David



There can be lots of arguments why one designs backwards study and not forward one. In my case, I am responsible for a lot of patients, going through my department, and need form time to time to have quality control of our patients management. It would have been nice to have a quarter of a million $ and 3 years time to carry on a study, but that's not reality.



Sorry.



And now for your question.



As my objective is geriatric patients, and my data includes general inter medicine ward cliental I like to reduce the noise younger and far healthier patients introduces into my data.

By matching some crucial parameters like age, sex, medication and disease, I may get answers to my questions.



As to my anagram. It is just for fun and nothing else.



As to the reference to http://personalpages.manchester.ac.uk/staff/mark.lunt/optmatch.html

I installed the files, but can not find the command in the menus.




*¸..· ´¨)) -:¦:-        *
   ¸.·´ .
 (( -:¦:- * Ishay *  -:¦:-
   ´·..          ..·´
              ((¸¸.·´* -:¦:-

_________________________________________________________-


Matching is an element of the design of a study, planned before the data is collected, and should be done for efficiency, not control. If you already have the data, you gain nothing by matching. You have a sample size of 2,500. If you match these data in the way you have indicated, you will end up with a matched sample size of 1,200. Why would you want to discard over half of your data?

You should analyse the data as they are and control for age, sex, etc in the analysis.


______________________________________________
Kieran McCaul MPH PhD
WA Centre for Health & Ageing (M573)
University of Western Australia
Level 6, Ainslie House
48 Murray St
Perth 6000
Phone: (08) 9224-2140
Fax: (08) 9224 8009
email: kamccaul@meddent.uwa.edu.au
http://myprofile.cos.com/mccaul
http://www.researcherid.com/rid/B-8751-2008
______________________________________________
Epidemiology is so beautiful and provides such an important perspective on human life and death,
but an incredible amount of rubbish is published.  Richard Peto (2007)

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Ishay Barat
Sent: Sunday, 15 March 2009 1:28 AM
To: statalist@hsphsun2.harvard.edu
Subject: st: CASE-CONTROL STUDY

HELLO



I've got a data set containing about 2500 patients, of which 300 have my
interest (Group A).

I would like to extract a sample of 900 patients (Group B) out of the data
set that match Group A in age, sex and some other parameters. A Classical
Case-Control study with 3 controllers for each case.



Is anybody have a clue how the syntax look like??






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 (( -:¦:- * Ishay *  -:¦:-
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              ((¸¸.·´* -:¦:-

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