<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Hi James,<div class=""><br class=""></div><div class="">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.</div><div class=""><br class=""></div><div class="">Morrissey, M. B. (2016). Meta-analysis of magnitudes, differences and variation in evolutionary parameters. J. Evol. Biol. 29, 1862-1904.</div><div class=""><br class=""></div><div class="">Morrissey, M. B. (2016).. Rejoinder: Further considerations for meta-analysis of transformed quantities such as absolute values. J. Evol. Biol. , 29: 1922–1931.</div><div class=""><br class=""></div><div class="">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.</div><div class=""><br class=""></div><div class="">Cheers,</div><div class="">Dan</div><div class="">
<div dir="auto" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none; caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">_______________<br class=""><br class="">Dr. Daniel Noble <br class="">Senior Lecturer<br class=""><br class="">Division of Ecology and Evolution (office W317),<br class="">Research School of Biology,<br class="">College of Science,<br class="">Robertson Building, <br class="">46 Sullivans Creek Road,<br class="">The Australian National University<br class="">Canberra, ACT 2600<br class="">Australia<br class=""><br class=""> T +61 02 6125 0423<br class="">M +61 430 290 053<br class=""><a href="mailto:daniel.noble@anu.edu.au" class="">daniel.noble@anu.edu.au</a><br class="">Noble Lab Webpage: www.nobledan.com<br class="">RSB: https://biology.anu.edu.au<br class=""><br class="">CRICOS Provider #00120C<br class=""></div></div><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none; caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);"></span><br class="Apple-interchange-newline" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none;"><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none;"></span><span><img apple-inline="yes" id="7F6FDE95-CCD2-4C8F-ABF7-8217433B90E3" src="cid:image001.png@01D778A0.2F1C4000" class=""></span>
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<div style=""><br class=""><blockquote type="cite" class=""><div class="">On 12 Feb 2022, at 12:24 pm, James Pustejovsky <<a href="mailto:jepusto@gmail.com" class="">jepusto@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">Hi meta-analysis folks,<br class=""><br class="">I have a kind of vague question about something I've run across a few<br class="">times. There are some (perhaps rare) situations where investigators are<br class="">interested in the absolute magnitude of an effect but where the sign or<br class="">direction of the effect is arbitrary or not meaningful. Consequently,<br class="">meta-analysts of such effects might like to work with _unsigned_ effect<br class="">size estimates rather than the estimates that describe both magnitude and<br class="">direction. However, taking the absolute value of an estimate changes its<br class="">sampling distribution--potentially quite drastically!--in a way that would<br class="">make conventional meta-analytic models<br class="">(fixed/common/random/multi-level/multi-variate) perform rather poorly.<br class=""><br class="">Does anyone know of work on methods for synthesis of unsigned effects, that<br class="">actually account for the consequences of using absolute effect size<br class="">estimates?<br class=""><br class="">James<br class=""><br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>[[alternative HTML version deleted]]<br class=""><br class="">_______________________________________________<br class="">R-sig-meta-analysis mailing list<br class=""><a href="mailto:R-sig-meta-analysis@r-project.org" class="">R-sig-meta-analysis@r-project.org</a><br class="">https://stat.ethz.ch/mailman/listinfo/r-sig-meta-analysis<br class=""></div></div></blockquote></div><br class=""></body></html>