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Hi, Is it possible to perform the test for residual heterogeneity on a model fitted with lme (nlme package) analogue to what is obtained in the rma.mv model output? Thanks, Gabri [[alternative HTML version deleted]]

Dear all, Could you provide an explanation or an example on why 'W' (for rma.mv) or 'weights' (for rma.uni) should be applied in a meta-analytic model? If I understand correctly, one should in principle "weight" the observation...

Hi all, I am performing a meta-analysis similar to the example reported in Konstantopoulos (2011) presented in metafor website <http://www.metafor-project.org/doku.php/analyses:konstantopoulos2011>. I am using the following structure for the random part (1...

Dear Mekides, I think this is a common issue in agricultural and ecological meta-analyses. But I am not sure the solution to your problem depends on metafor. However, based on my experience, there are few options to be considered...

Dear all, My colleagues and I would like to report pseudo-R2 values in the results of a meta-analysis. We are wondering 1) if our approach to calculate R2 for meta-analytical models is overall correct, and 2) if...

Dear all, Following Wolfgang instructions on multimodel inference with glmulti ( http://www.metafor-project.org/doku.php/tips:model_selection_with_glmulti), I came out with the following output in my analysis: > output_SLA Estimate Uncond. variance Nb models Importance...

Ok thanks Wolfgang, I actually noted it is the same of simply adding/subtratting the 'alpha=0.05' term to the estimate (?). Other predictors are scaled in the regression and thereby the intercept is the true outcome when all predictors...

Dear all, My research group is carrying out an ecological meta-analysis where primary studies have multiple treatment (doses) compared to a single control group. For this reason, we are fitting the model (res1), as follow: calc.v <- function(x...

Dear all, A methodological - rather than practical/coding - question: is there any meta-analytical technique to quantify the relationship of effect sizes for studies reporting two or more variable of interest for the meta-analysis? Some explanation: I am conducting...

Dear Michael, That shouldn't be the issue, because I re-compute V after I sorted the rows and before I fitted the model (not showed in my previous email). Please find attached a minimal data-set and reproducible R...

Hi Greta (all), Thanks for suggesting netmeta, it sound like an interesting alternative. However, I am wondering if the studies I am dealing with (e.g. as the one described in my previous email) are comparable to 'multiple-arms studies...

Dear Wolfgang, Thank you very much for the info and sorry for proposing a 'frequently asked question'. When reading at your piece on Berkey et al. (1998), I think the part I am more interested about is the "Variance component...

Dear Wolfgang & James (all), Thanks for the code Wolfgang, it works fine and it is indeed possible (at least in terms of coding and modeling) to fit the model accounting for "multiple controls" within each study (so, metafor can indeed...

Dear James (all), Thanks for your ideas, very appreciated. I understand what you mean, but SLA can be calculated on different species which are likely to report very different magnitude depending on the species. Plus I think the ratios calculated...

Dear all, I noticed that the results of my rma.mv() model strongly changes when the dataframe rows are arranged in a different order. This is new to me and I can?t really understand why. I thought it was...

Dear all, Do you think it is possible to perform a multilevel meta-analysis without sampling variance (from both the conceptual and the statistical point of view), using only the number of replicates to weight the importance of studies? I...

Dear James, So, concerning the code I have put above, one simply need to sort the ctrl_id with ascending order before computing V? Something like: data1<-data1%>%arrange(ctrl_id) # ...using dplyr That way the dataframe should be ordered...

I am using anova() to perform the ombibus test by setting the "btt" argument to estimate the amount of residual heterogeneity reduced for each moderator in an rma.mv model. For example, if I interpret this correctly, in a model...

Hi Luca, In my opinion, and based on what you described, this is what the estimate of model B seems to suggest (i.e. that the estimated effect size is not significantly different from 0 when the moderator has a...

Hi Koenraad, I agree with what Michael put above. Not sure this is what you are looking for, but I posted a similar question some time ago and got a code from Wolfgang to build variance-covariance matrix based on...