From: Bob Green <bgreen_at_dyson.brisnet.org.au>

Date: Fri 26 Jan 2007 - 21:26:45 GMT

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Sat Jan 27 08:28:54 2007

Date: Fri 26 Jan 2007 - 21:26:45 GMT

Any further clarification is much appreciated,

Bob Green

., At 02:57 PM 26/01/2007 +0100, Peter Dalgaard wrote:

>Michael Dewey wrote:

*> > At 09:04 26/01/2007, Bob Green wrote:
**> >
**> >> I wanted to compare odds ratio across studies and tried to replicate
**> >> the results from a study but have not been able to determine how to
**> >> do this in R.
**> >>
**> >> The study reported a sample of 961 men, of whom 41 had a disorder.
**> >> The reported raw odds ratio was 6.52 (4.70-9.00)
**> >>
**> >
**> > For an odds ratio you require two odds from which you form the odds ratio.
**> > You only have one odds.
**> > Do you have another one lying around somewhere?
**> >
**>Alternatively, the odds ratio presumably compares two groups. If you
**>know the group sizes, the two odds ratios may be reconstructed. If I
**>make a wild guess that the groups are roughly equal, I might get
**>
**> > M <- cbind(c(460,460),c(6,35))
**> > M
**> [,1] [,2]
**>[1,] 460 6
**>[2,] 460 35
**> > fisher.test(M)
**>
**> Fisher's Exact Test for Count Data
**>
**>data: M
**>p-value = 7.406e-06
**>alternative hypothesis: true odds ratio is not equal to 1
**>95 percent confidence interval:
**> 2.393209 17.104976
**>sample estimates:
**>odds ratio
**> 5.824317
**>
**>Judging by the c.i., the groups are probably *not* of similar size. I
**>suppose that the high-incidence group is a bit smaller so that the count
**>of advverse events is more similar. M <- cbind(c(803,117),c(21,20)) is a
**>bit more like it, but your (Bob's) confidence interval is narrower even
**>than this.
**>
**>--
**> O__ ---- Peter Dalgaard Ã˜ster Farimagsgade 5, Entr.B
**> c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
**> (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
**>~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk) FAX: (+45) 35327907
*

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