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