No, you are not missing anything. You can not adjust forfactors included in the match (assuming the match is exact).
John
John David Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)
>>> "Ayansina, Dolapo" <[log in to unmask]> 10/1/2009 12:27 PM >>>
Dear listers,
I'm posting on behalf of a colleague.
All responses to Kirsten Harrild please.
________________________________
Dear all,
I have conducted a matched case-control study, with 3 controls for every case, individually matched on year of birth. I have analysed the data using conditional logistic regression. I have now been asked to adjust for year of birth in the analysis. My understanding is that because I have matched for year of birth, I will not be able to enter this variable in the model - there will be no discordancy between cases and controls, making it impossible to come up with an effect size. Am I missing something?
Any advice would be most appreciated.
Please reply to [log in to unmask]<mailto:[log in to unmask]>.
Best wishes,
Kirsten Harrild
The University of Aberdeen is a charity registered in Scotland, No SC013683.
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