[R-meta] Funnel Plots for Multilevel Meta
Dear Michael and Wolfgang. at the end of Egger's regression / funnel plot thread, Wolfgang said: "To what extent such a plot is indicative of publication bias / small study effects is a different issue" Could you please say more on this topic? Particularly I am interested in this: is a plot with 8 effects informative? Or a plot with less than 20 effects? Best, Valeria On Fri, Dec 11, 2020 at 11:28 PM Viechtbauer, Wolfgang (SP) <
wolfgang.viechtbauer at maastrichtuniversity.nl> wrote:
A funnel plot is simply a plot of the estimates against their standard errors (or some other measure of precision). So one can draw such a plot whether there are multiple estimates from the same study or not. Hence, funnel() in metafor will happily do so: library(metafor) dat <- dat.konstantopoulos2011 res <- rma.mv(yi, vi, random = ~ 1 | district/school, data=dat) res funnel(res) One could indicate (with different colors or plotting symbols) which estimates belong to the same study. cols <- palette.colors(length(unique(dat$district)), palette="Alphabet") cols <- cols[as.numeric(factor(dat$district))] funnel(res, col=cols) Then one can see how points from the same study (or in this case, 'district') cluster together. To what extent such a plot is indicative of publication bias / small study effects is a different issue (but the same applies even to simpler meta-analyses with a single estimate per study). Best, Wolfgang
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On Behalf Of Dylan Johnson Sent: Friday, 11 December, 2020 20:03 To: Michael Dewey; r-sig-meta-analysis at r-project.org Subject: Re: [R-meta] Funnel Plots for Multilevel Meta Hi Michael, Would it not be nonsensical to have multiple effects from the same article in the funnel plot though? With the Egger's regression I was able to accommodate the fact that their
is
nonindependence of the effects, but am unsure how to proceed with a funnel plot. Dylan Dylan Johnson, MSc MA Student, School and Clinical Child Psychology Department of Applied Psychology and Human Development University of Toronto 252 Bloor Street West Toronto, ON M5S 1V6 From: Michael Dewey<mailto:lists at dewey.myzen.co.uk> Sent: December 11, 2020 6:12 AM To: Dylan Johnson<mailto:dylanr.johnson at mail.utoronto.ca>; r-sig-meta- analysis at r-project.org<mailto:r-sig-meta-analysis at r-project.org> Subject: Re: [R-meta] Funnel Plots for Multilevel Meta Dear Dylan Perhaps I misunderstand you but if you have the data for a regression type test like Egger's do you not just plot that? The funnel() function in metafor does that and I am sure equivalent solutions can be found in meta and many other packages. Michael On 11/12/2020 01:14, Dylan Johnson wrote:
Hello, Thanks everyone for helping me sort out the Egger's test with
multi-level
meta modelling!
Is there any option in R for producing Funnel plots that are appropriate
for the nonindependence? I imagine that the standard funnel plot would be deceiving if it came from a multi-level design.
Many thanks! Best, Dylan Dylan Johnson, MSc MA Student, School and Clinical Child Psychology Department of Applied Psychology and Human Development University of Toronto 252 Bloor Street West Toronto, ON M5S 1V6
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