[R-meta] Awkward results while conducting a Meta Analytic Reliability Generalization study by metafor package

[Viechtbauer Wolfgang (SP)]

For measure="AHW" (and all else equal), the relationship between the transformed values and the standard errors is linear:

k <- 100
ai <- runif(k, .5, .9)
mi <- rep(10, k)
ni <- rep(100, k)

dat <- escalc(measure="AHW", ai=ai, mi=mi, ni=ni)
plot(dat$yi, dat$vi)
plot(dat$yi, sqrt(dat$vi))

And by default, this is the relationship the regression test actually examines.

Best,
Wolfgang

-----Original Message-----
From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces at r-project.org] On Behalf Of Davut CANLI
Sent: Friday, 27 October, 2017 10:44
To: r-sig-meta-analysis
Subject: Re: [R-meta] Awkward results while conducting a Meta Analytic Reliability Generalization study by metafor package

Thanks for your quick response Professor Wolfgang. I agree your first statements that there is indeed a direct relationship between the transformed alpha and its corresponding variance as you have already mentioned that alpha itself is being used in the calculation of variance component. However, this functional relation is quadratic and it does not guarantee that there we should expect a linear correlation between them. I will give a try some simulations to better understandings. I guess there are still things to do on this issue. (For now better to use other possible predictors as your suggestion).

By the way, the funnel plot issue has been solved. It seems an eye illusion caught me. :(

Thanks.

Davut CANLI 
-- 
Ordu University 
Faculty of Arts and Sciences 
Department of Mathematics