[R-meta] Awkward results while conducting a Meta Analytic Reliability Generalization study by metafor package
Davut CANLI
davutcanli at odu.edu.tr
Thu Oct 26 09:05:22 CEST 2017
Dear all,
There are two common methods (Bonett's transformation and Hakstian and Whalen transformation) while conducting an RG study when the issued reliability coefficient is Cronbach's alpha. The problem occurs when I use the regtest or ranktest functions of metafor. Using one method (say Bonett's transformation, ABT), the output of the regtest (or ranktest) suggest that there is no evidence for publication bias by providing a p-value bigger than 0.05. On the other hand the use of other method ("AHW") suggests signicant evidence (p<.0001) for a possible publication bias (which I believe in fact this should be correct).
Another thing is the output of the funnel command. Even though I have not a value of coefficient alpha bigger than one in my data set, there I see a value that seems bigger than one on the output of the funnel.
Are these some kind of bugs of functions in code or something that I still have some misunderstandings on the subject.
############################## Bonett's Transformation #####################
> regtest(MetaOBO_ABT)
Regression Test for Funnel Plot Asymmetry
model: mixed-effects meta-regression model
predictor: standard error
test for funnel plot asymmetry: z = -0.5277, p = 0.5977
> ranktest(MetaOBO_ABT)
Rank Correlation Test for Funnel Plot Asymmetry
Kendall's tau = -0.0108, p = 0.8664
Warning message:
In cor.test.default(yi.star, vi, method = "kendall", exact = TRUE) :
Cannot compute exact p-value with ties
############################## Using Haks. & Wha. Transformation #####################
> regtest(MetaOBO_AHW)
Regression Test for Funnel Plot Asymmetry
model: mixed-effects meta-regression model
predictor: standard error
test for funnel plot asymmetry: z = -4.1625, p < .0001
> ranktest(MetaOBO_AHW)
Rank Correlation Test for Funnel Plot Asymmetry
Kendall's tau = -0.1980, p = 0.0020
############################### Funnel Plot ##############################################
In attached.
Thanks all in advance.
Davut CANLI
--
Ordu University
Faculty of Arts and Sciences
Department of Mathemathics
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