[R] interpreting weight in meta-analysis of proportion

[petretta at unina.it]

Prof. Dewey, sorry for the trivial question and many thank for the replay.


> Using which package?

In this case I used the meta package, but I know that for all but the
DerSimonian-Laird method the R function rma.uni of R package metafor is
called internally.

> What did you expect the weights to sum to, I wonder.

I think that, to better explain the influence of single study in pooling
the effect size, the weight are presented as percentage of the sum of
total weight of each study, but I ask for a confirm. Nevertheless, I ask
if it is possible to obtain for each study the value of the absolute
weight, other than the relative weight, or at least the absolute value of
the sum of the weights.

Sincerely

Mario Petretta
>Department of Translational Medical Sciences
>Naples University Federico II
>Italy
>




Message: 2
Date: Thu, 17 Apr 2014 12:43:06 +0100
From: Michael Dewey <info at aghmed.fsnet.co.uk>
To: petretta at unina.it, r-help at r-project.org
Subject: Re: [R] interpreting weight in meta-analysis of proportion
Message-ID: <Zen-1Wakio-0009TP-RO at smarthost01b.mail.zen.net.uk>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 16:30 16/04/2014, petretta at unina.it wrote:
>Dear all,
>
>I use R 3.0 for Windows.
>
>I performed a meta-analysis of the prevalence (single proportion)
>reported in 14 different studyes using the command:
>
>res<-metaprop(case,n,sm="PFT", comb.fixed=FALSE, comb.random=TRUE,
>studlab<- paste(Study))

Using which package?


>print(res)
>
>A referee ask a brief explanation of the W-statistic reported in the
>results, in particular, why the summ of the individual weights of all
>the studies is 100%.

What did you expect the weights to sum to, I wonder.

>Any suggestion is welcome.
>
>
>--
>Mario Petretta
>Department of Translational Medical Sciences
>Naples University Federico II
>Italy
>
>

Michael Dewey
info at aghmed.fsnet.co.uk
http://www.aghmed.fsnet.co.uk/home.html