[R-meta] unsigned effect sizes

[Viechtbauer, Wolfgang (SP)]

Hi James,

I think this is also related:

https://doi.org/10.1207/s15327043hup1201_1

Best,
Wolfgang

>-----Original Message-----
>From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-project.org] On
>Behalf Of Daniel Noble
>Sent: Saturday, 12 February, 2022 2:34
>To: James Pustejovsky
>Cc: R meta
>Subject: Re: [R-meta] unsigned effect sizes
>
>ATTACHMENT(S) REMOVED: ATT00001.txt
>
>Hi James,
>
>A great question! Yes, this is something quite common in ecology and evolution
>meta-analyses. There are some nice papers you may want to consult by Mike
>Morrissey. Here are a few references.
>
>Morrissey, M. B. (2016). Meta-analysis of magnitudes, differences and variation
>in evolutionary parameters. J. Evol. Biol. 29, 1862-1904.
>
>Morrissey, M. B. (2016).. Rejoinder: Further considerations for meta-analysis of
>transformed quantities such as absolute values. J. Evol. Biol. , 29: 1922–1931.
>
>Basically it involves transforming ‘post-analysis’ to a folded normal. I’ve used
>it myself in a Bayesian context. It’s quite easy to do there. Hope this is useful
>and what you’re thinking about.
>
>Cheers,
>Dan
>_______________
>
>Dr. Daniel Noble
>Senior Lecturer
>
>Division of Ecology and Evolution (office W317),
>Research School of Biology,
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>On 12 Feb 2022, at 12:24 pm, James Pustejovsky <jepusto using gmail.com> wrote:
>
>Hi meta-analysis folks,
>
>I have a kind of vague question about something I've run across a few
>times. There are some (perhaps rare) situations where investigators are
>interested in the absolute magnitude of an effect but where the sign or
>direction of the effect is arbitrary or not meaningful. Consequently,
>meta-analysts of such effects might like to work with _unsigned_ effect
>size estimates rather than the estimates that describe both magnitude and
>direction. However, taking the absolute value of an estimate changes its
>sampling distribution--potentially quite drastically!--in a way that would
>make conventional meta-analytic models
>(fixed/common/random/multi-level/multi-variate) perform rather poorly.
>
>Does anyone know of work on methods for synthesis of unsigned effects, that
>actually account for the consequences of using absolute effect size
>estimates?
>
>James