Dear Kevin,

Im not familiar with the package metafor. Im familiar with package meta,
although, which gives nice graphical output. I did some analysis with
observational studies with stata back in 2006 in my master degree. Similar
to your case I did have data from case-control, cross-sectional, and cohort
investigations. At the time, the odds ratio were very popular to summarize
data for trials too. Therefore I decided to use the OR for all
investigations in way compare results and summarize them all. OR may not
give the exact same results as RR but may give results close enough. Another
way around is not summarize considering the potential bias in the summary
estimate and the few studies included in the review.  :(

Considering the earlier answer by Wolfgan, you could stratifiy the result by
design if possible or you could estimate the standrd error in each point
estimate of each investigation included and use the metagen function in meta
package. The input of this function is OR (or RR) and SE (or logSE memory
failed :-) ).

Perhaps it will help if I got the problem right!

Good luck,

Dr. Pedro Emmanuel A. A. do Brasil
Instituto de Pesquisa Clínica Evandro Chagas
Fundação Oswaldo Cruz
Rio de Janeiro - Brasil


2010/1/27 <r-sig-epi-request@stat.math.ethz.ch>

> Send R-sig-Epi mailing list submissions to
>        r-sig-epi@stat.math.ethz.ch
>
> To subscribe or unsubscribe via the World Wide Web, visit
>        https://stat.ethz.ch/mailman/listinfo/r-sig-epi
> or, via email, send a message with subject or body 'help' to
>        r-sig-epi-request@stat.math.ethz.ch
>
> You can reach the person managing the list at
>        r-sig-epi-owner@stat.math.ethz.ch
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of R-sig-Epi digest..."
>
>
> Today's Topics:
>
>   1. meta-analysis (Lu, Kevin)
>   2. Re: meta-analysis (Viechtbauer Wolfgang (STAT))
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 27 Jan 2010 09:25:05 +0100
> From: "Lu, Kevin" <kevin.lu@wur.nl>
> To: <r-sig-epi@stat.math.ethz.ch>
> Subject: [R-sig-Epi] meta-analysis
> Message-ID:
>        <124584AFB3A4D449834B67071ACCD55501A7D9C7@scomp0040.wurnet.nl>
> Content-Type: text/plain
>
> To someone who could help me:
>
> I am a PhD student, working in the Wageningen University, the
> Netherlands. I am now using metafor package to do meta-analysis.
>
> Since there are few studies conducted on my topic, I have to combine the
> results from 5 case-control studies and 1 cohort study. But I do not
> know how to do it.
>
> I tried this way, first, use the escalc (measure="OR", ai, bi, ci, gi)
> to calculate the effect estimate of yi and variance of vi.
>
> I could extract the RR and 95% confidence interval from the cohort study
> to get the point estimate of LnRR and SE.
>
> but I can not combine the results from case-control study and the
> results from cohort study due to the difference of vi and SE.
>
> For example, if I use rma(yi, vi, data,), I can not get vi (variance)
> for the cohort study. I can only get SE for cohort study. How could
> solve it?
>
> Thanks for your time.
>
> Best wishes,
>
> Yingchang (Kevin) Lu
>
> PhD student,
>
> Division of Human Nutrition
>
> Wageningen University
>
> Tel: 0031-317-485300
>
> Fax:0031-317-482782
>
>
>        [[alternative HTML version deleted]]
>
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 27 Jan 2010 10:43:05 +0100
> From: "Viechtbauer Wolfgang (STAT)"
>        <Wolfgang.Viechtbauer@STAT.unimaas.nl>
> To: "r-sig-epi@stat.math.ethz.ch" <r-sig-epi@stat.math.ethz.ch>
> Subject: Re: [R-sig-Epi] meta-analysis
> Message-ID:
>        <077E31A57DA26E46AB0D493C9966AC7305C6052B09@UM-MAIL4112.unimaas.nl>
> Content-Type: text/plain; charset="us-ascii"
>
> Dear Kevin,
>
> The standard error of the estimate (SE) is the square root of the sampling
> variance of the estimate (vi). So, just square 'SE' and use that for 'vi'.
>
> Best,
>
> --
> Wolfgang Viechtbauer                        http://www.wvbauer.com/
> Department of Methodology and Statistics    Tel: +31 (43) 388-2277
> School for Public Health and Primary Care   Office Location:
> Maastricht University, P.O. Box 616         Room B2.01 (second floor)
> 6200 MD Maastricht, The Netherlands         Debyeplein 1 (Randwyck)
>
>
> ----Original Message----
> From: r-sig-epi-bounces@stat.math.ethz.ch
> [mailto:r-sig-epi-bounces@stat.math.ethz.ch] On Behalf Of Lu, Kevin
> Sent: Wednesday, January 27, 2010 09:25 To: r-sig-epi@stat.math.ethz.ch
> Subject: [R-sig-Epi] meta-analysis
>
> > To someone who could help me:
> >
> > I am a PhD student, working in the Wageningen University, the
> > Netherlands. I am now using metafor package to do meta-analysis.
> >
> > Since there are few studies conducted on my topic, I have to combine
> > the results from 5 case-control studies and 1 cohort study. But I do
> > not know how to do it.
> >
> > I tried this way, first, use the escalc (measure="OR", ai, bi, ci,
> > gi) to calculate the effect estimate of yi and variance of vi.
> >
> > I could extract the RR and 95% confidence interval from the cohort
> > study to get the point estimate of LnRR and SE.
> >
> > but I can not combine the results from case-control study and the
> > results from cohort study due to the difference of vi and SE.
> >
> > For example, if I use rma(yi, vi, data,), I can not get vi (variance)
> > for the cohort study. I can only get SE for cohort study. How could
> > solve it?
> >
> > Thanks for your time.
> >
> > Best wishes,
> >
> > Yingchang (Kevin) Lu
> >
> > PhD student,
> >
> > Division of Human Nutrition
> >
> > Wageningen University
> >
> > Tel: 0031-317-485300
> >
> > Fax:0031-317-482782
> >
> >
> >       [[alternative HTML version deleted]]
> >
> > _______________________________________________
> > R-sig-Epi@stat.math.ethz.ch mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-sig-epi
>
>
>
> ------------------------------
>
> _______________________________________________
> R-sig-Epi mailing list
> R-sig-Epi@stat.math.ethz.ch
> https://stat.ethz.ch/mailman/listinfo/r-sig-epi
>
>
> End of R-sig-Epi Digest, Vol 38, Issue 3
> ****************************************
>

	[[alternative HTML version deleted]]

