Hello, I am running a correlational meta-analysis and I was wondering if there are guidelines for which measure to use as a predictor in Egger's test with multilevel models. I have encountered a few sources (e.g. the paper by James - Testing for funnel plot asymmetry of standardized mean differences) on how using measures of variance may be problematic with logs odds ratios and standardised mean difference effect size estimates, but does anyone know if there's such research for meta-analyses examining correlations? The only reference I found was here: https://stat.ethz.ch/pipermail/r-sig-meta-analysis/2020-May/002086.html Thank you, Catia
[R-meta] correlational meta-analyses and Egger's regression test
2 messages · Cátia Margarida Oliveira, James Pustejovsky
Hi Catia, I don't know of any studies on this. But the statistical theory here is pretty straight-forward, so perhaps it's not necessary to do simulations to confirm. For the sample Pearson correlation coefficient r, the (estimated) standard error is (1 - r^2) / sqrt(N - 1), which is strongly correlated with the point estimator. This implies that there will tend to be an asymmetric funnel plot and non-zero slope to Egger's regression (or the multi-level/multi-variate extensions thereof) even in the absence of selective reporting. To avoid this artifact, Wolfgang suggests using 1 / sqrt(N - 1) as the predictor in Egger's regression because then it will be independent of the effect size estimator. Alternately, you could do the analysis using Fisher's z transformation. The z transformed correlation has standard error 1 / sqrt(N - 3), which will be independent of the effect size estimator. James On Sat, Jan 22, 2022 at 11:53 AM C?tia Margarida Oliveira <
catiamargarid at gmail.com> wrote:
Hello, I am running a correlational meta-analysis and I was wondering if there are guidelines for which measure to use as a predictor in Egger's test with multilevel models. I have encountered a few sources (e.g. the paper by James - Testing for funnel plot asymmetry of standardized mean differences) on how using measures of variance may be problematic with logs odds ratios and standardised mean difference effect size estimates, but does anyone know if there's such research for meta-analyses examining correlations? The only reference I found was here: https://stat.ethz.ch/pipermail/r-sig-meta-analysis/2020-May/002086.html Thank you, Catia [[alternative HTML version deleted]]
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