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.-É. Parent, Eng., Ph.D.
Department of Soils and Agrifood Engineering, Université Laval
Canada
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