[R-meta] Threshold values for Cook's Distances and DFBETAS
Dear Theresa My feeling is that these diagnostics are better seen as identifying values which may benefit from further investigation. If I was concerned that they were unduly influential in the model I might try fitting leave-one-out models but since those models are essentially data-driven they are also only useful in an exploratory sense. So, even if there is a formula I would be sceptical about its value in answering the scientific question. Michael
On 29/09/2022 21:35, Th?lking, Theresa wrote:
Hello everybody, I am trying to apply the outlier and influence diagnostics as described by Viechtbauer and Cheung (2010) on a meta-analysis I conducted, using a four-level random-effects model with 528 included effect sizes. I have calculated the Cook's Distances and DFBETAS in R, using the functions for model diagnostics for rma.mv objects as described here: https://wviechtb.github.io/metafor/reference/influence.rma.mv.html However, I don't know how to decide about which studies are influential based on these values. I read the paper by Viechtbauer and Cheung, but I don't quite understand it. Is there some kind of formula to determine the threshold values of CD and DFBETAS for a meta-analytic model with k outcomes? Thanks in advance for your help. Best, Theresa [[alternative HTML version deleted]]
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