R help - Jan 2011 - Metafor vs Meta vs Spreadsheet: wrong numbers

Hello,

I experimented the Metafor and Meta packages in the scope of replacing  Excel 
for meta-analysis. I performed the first working example provided  in Michael 
Borenstein's book "Introduction to Meta-Analysis" with Excel, 
Metafor and Meta.
The numbers given by my spreadsheet, which I  validated from Borenstein's
book,
conrespond quite closely to those  given by Meta, but are different from those 
obtained using Metafor. For  the fixed effect, I infer that the differences are 
related to numerical  issues, but for the random effect, the numbers are 
considerably  different. Unfortunately, I could not find where I made it wrong. 
I  would be grateful if someone would have a look at my calculations.

Here are the meta-analysis commands:

### USING METAFOR
library(metafor)
( dat<-escalc(m1i=m1i, sd1i=sd1i, n1i=n1i, m2i=m2i, sd2i=sd2i,  n2i=n2i, 
measure="SMD", data=metaData, append=T) ) # COMPUTE EFFECT SIZE
( res<-rma.uni(yi,vi,data=dat,method="HE", level=95) ) ### RANDOM
EFFECT
( res<-rma.uni(yi,vi,data=dat,method="FE", level=95) )  ### FIXED
EFFECT

### USING META
( res<-metacont(metaData[,3], metaData[,1], metaData[,2], metaData[,6], 
metaData[,4], metaData[,5],
    studlab=rownames(metaData),sm="SMD",
    level = 0.95, level.comb = 0.95,
    comb.fixed=TRUE, comb.random=TRUE,
    label.e="Experimental", label.c="Control",
    bylab=rownames(metaData)) )

The whole R script is temporarly available at http://bit.ly/eYesbZ
The spreadsheet is temporarly available at http://bit.ly/fAYWPo

Kind regards, 

S.-?. Parent, Eng., Ph.D.
Department of Soils and Agrifood Engineering, Universit? Laval
Canada

Dear Serge-?tienne,

Try:

res <- rma.uni(yi, vi, data=dat, method="DL")

for the random-effects model when using the metafor package. You used
method="HE" -- this will give you a different estimator of tau^2 then
the one used in the meta package.

Best,

--
Wolfgang Viechtbauer
Department of Psychiatry and Neuropsychology
School for Mental Health and Neuroscience
Maastricht University, P.O. Box 616
6200 MD Maastricht, The Netherlands
Tel: +31 (43) 368-5248
Fax: +31 (43) 368-8689
Web: http://www.wvbauer.com


----Original Message----
From: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org] On Behalf Of Serge-?tienne Parent
Sent: Wednesday, January 12, 2011 18:18 To: r-help at r-project.org
Subject: [R] Metafor vs Meta vs Spreadsheet: wrong numbers
> Hello,
>
> I experimented the Metafor and Meta packages in the scope of
> replacing  Excel for meta-analysis. I performed the first working
> example provided  in Michael Borenstein's book "Introduction to
> Meta-Analysis" with Excel,  Metafor and Meta. The numbers given by my
> spreadsheet, which I  validated from Borenstein's book, conrespond
> quite closely to those  given by Meta, but are different from those
> obtained using Metafor. For  the fixed effect, I infer that the
> differences are related to numerical  issues, but for the random
> effect, the numbers are considerably  different. Unfortunately, I
> could not find where I made it wrong. I  would be grateful if someone
> would have a look at my calculations.
>
> Here are the meta-analysis commands:
>
> ### USING METAFOR
> library(metafor)
> ( dat<-escalc(m1i=m1i, sd1i=sd1i, n1i=n1i, m2i=m2i, sd2i=sd2i,
>   n2i=n2i, measure="SMD", data=metaData, append=T) ) # COMPUTE
EFFECT
> SIZE ( res<-rma.uni(yi,vi,data=dat,method="HE", level=95) )
###
> RANDOM EFFECT ( res<-rma.uni(yi,vi,data=dat,method="FE",
level=95) )
> ### FIXED EFFECT
>
> ### USING META
> ( res<-metacont(metaData[,3], metaData[,1], metaData[,2],
>   metaData[,6], metaData[,4], metaData[,5],
>     studlab=rownames(metaData),sm="SMD", level = 0.95, level.comb
>     0.95, comb.fixed=TRUE, comb.random=TRUE,
label.e="Experimental",
> label.c="Control", bylab=rownames(metaData)) )
>
> The whole R script is temporarly available at http://bit.ly/eYesbZ
> The spreadsheet is temporarly available at http://bit.ly/fAYWPo
>
> Kind regards,
>
> S.-?. Parent, Eng., Ph.D.
> Department of Soils and Agrifood Engineering, Universit? Laval Canada