[R] Classic fail-safe N
wangnaike1989 at gmail.com
Mon Jun 26 13:29:00 CEST 2017
Will do, thanks!
Viechtbauer Wolfgang (SP)
<wolfgang.viechtbauer at maastrichtuniversity.nl>于2017年6月26日
> I would suggest to post this to the (recently created) R-sig-meta-analysis
> mailing list. See:
> >-----Original Message-----
> >From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Naike
> >Sent: Monday, June 26, 2017 08:32
> >To: R-help at r-project.org
> >Subject: [R] Classic fail-safe N
> >Hi all,
> >I was conducting a meta-analysis of single proportions(i.e. without a
> >control group) using the metafor package. When I performed a classic
> >fail-safe N, I noticed that the result (the number of missing studies that
> >would bring p-value to the alpha, to be exact)was different than that I
> >in Comprehensive Meta-Analysis Version 2.0. I wonder why R and CMA got
> >different results.
> >*Below is the R code:*
> >dat=read.table("Your working directory\\Example.csv",header=T,sep=",")
> >transf.ies=escalc(xi=cases,ni=total,measure="PLO",data=dat) #I transform
> >the data using the logit transformation first. In CMA, it also uses the
> >logit transformation.
> >transf.pes=rma(yi,vi,data=transf.ies,method="DL",weighted=TRUE) #Pooling
> >individual effect sizes in the logit scale.
> >ranktest(transf.pes) #Performing the fail-safe N.
> >*Below are the results from R:*
> >Fail-safe N Calculation Using the Rosenthal Approach
> >Observed Significance Level: <.0001
> >Target Significance Level: 0.05
> >Fail-safe N: 8446
> >*Below are the Classic fail-safe N results from CMA:*
> >Z-value for observed studies 19.91594
> >P-value for observed studies 0.00000
> >Alpha 0.05000
> >Tails 2.00000
> >Z for alpha 1.95996
> >Number of observed studies 58.00000
> >Number of missing studies that would bring p-value to > alpha 5931.00000
> >Notice that I got 8446 in R and 5931 in CMA.
> >Can anyone shed some light on this discrepancy? Thank you!
> >You can find my data set here:
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