Dear James
Your question really boil down to whether you can estimate tau^2, the
between study variance of the effect sizes, if you only have p-values.
As far as I can see the answer has to be no.
Michael
On 16/01/2020 13:10, james poweraid wrote:
Hello,
I have a set of Z scores from an N=2 studies and I need to run a
meta-analysis across the two Z scores for many N variables. I do not have
effect sizes and SEs. I realize there are many different meta analysis
packages in R, but I only have Z scores and it seems to me this is
limiting. I am using the metap package because this very conveniently
accepts directly p values which I can get from my Z scores. I have applied
what is called in metap package the sumlog Fisher’s method Chi square (2
df).
I have three questions:
1. Is this the same as a fixed effect meta-analysis without weights?
2. Is there any way to do a random effects meta-analysis starting only
with Z scores?
3. Is there a way to get the I2 heterogeneity across studies from this
or from other packages? It looks like I need the estimates for this. Is
there another package that can easily get this using as input Z scores or P
values?
Data
library(metap)
zscores = cbind(c(4, 2, 0.1),c(5, 2.5, 0.1))
pvalues = apply(zscores, 1:2, function(x) 2*(pnorm( abs(x) ,
lower.tail=F)))
meta = apply(pvalues, MARGIN=1, FUN=sumlog)
Thank you much
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Michael
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