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 got
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:
https://drive.google.com/open?id=0B41wTxciaMqtTEJWZE9sX20wOXM
Best,
Naike
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I would suggest to post this to the (recently created) R-sig-meta-analysis mailing list. See: https://stat.ethz.ch/mailman/listinfo/r-sig-meta-analysis Best, Wolfgang>-----Original Message----- >From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Naike Wang >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 >got >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: >https://drive.google.com/open?id=0B41wTxciaMqtTEJWZE9sX20wOXM > >Best, >Naike
Will do, thanks! Viechtbauer Wolfgang (SP) <wolfgang.viechtbauer at maastrichtuniversity.nl>?2017?6?26? ??03:39???> I would suggest to post this to the (recently created) R-sig-meta-analysis > mailing list. See: > > https://stat.ethz.ch/mailman/listinfo/r-sig-meta-analysis > > Best, > Wolfgang > > >-----Original Message----- > >From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Naike > Wang > >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 > >got > >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: > >https://drive.google.com/open?id=0B41wTxciaMqtTEJWZE9sX20wOXM > > > >Best, > >Naike >[[alternative HTML version deleted]]