[R-meta] Publication bias with multivariate meta analysis

[Huang Wu]

Hi all,

I am conducting a multivariate meta-analysis using rma.mv. I want to test for publication bias.
I noticed in a previous post, Dr. Pustejovsky provided the following code for Egger’s test.

egger_multi <- rma.mv(yi = yi, V = sei^2, random = ~ 1 | studyID/effectID,
mods = ~ sei, data = dat)
coef_test(egger_multi, vcov = "CR2")

Because I conducted a multivariate meta-analysis assuming rho = 0.8, I wonder for the Egger’s test, Do I need to let V equals to the imputed covariance matrix?
Would anyone help me to see if my following code is correct? Thanks.

V_listm <- impute_covariance_matrix(vi = meta$dv,
                                    cluster = meta$Study.ID,
                                    r = 0.8)
egger_multi <- rma.mv(yi =Cohen.s.d, V = V_listm, random = ~ 1 | Study.ID/IID,
                      mods = ~ sqrt(dv), data = meta)
coef_test(egger_multi, vcov = "CR2")

Also, I have tried V = V_listm and V = dv, but it gave me different results. When I use V = V_Vlistm, my results suggest the effect was no longer statistically significant but when I use V = dv, my result is still significant.
Does that mean my results were sensitive to the value of rho? Thanks.

By the way, does anyone have any suggestions/codes for other methods of testing publication bias? Many thanks.

Best wishes
Huang

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