[R-meta] random effects MA with correlations
@c @ending from imbi@uni-freiburg@de
Thu Sep 13 11:44:20 CEST 2018
I agree with Wolfgang on all comments. I would like to add some thoughts
on the use of the Hartung-Knapp method.
The Hartung-Knapp method is not a viable option in meta-analyses with
very few studies (Bender et al., 2018); this is quite common in the
medical field. The reason is that the Hartung-Knapp method uses a
quantile from the t-distribution with 'number of studies minus 1'
degrees of freedom - in the extreme case of two studies one uses a
quantile of 12.71 (compared to 1.96 for the normal approximation).
Furthermore, in very rare situations with "too homogeneous" study
results the Hartung-Knapp method might lead to a smaller confidence
interval than the fixed effect meta-analysis (Schwarzer et al., 2016).
This seems somewhat counterintuitive.
P.S. I do not have a preference for any tau2 estimator. R package meta
uses the (nowadays criticized) DerSimonian-Laird estimator as default
for historic reasons / to be in agreement with RevMan 5 from Cochrane.
Bender R, Friede T, Koch A, et al. (2018): Methods for evidence
synthesis in the case of very few studies, Research Synthesis Methods,
Wiksten A, Rücker G, Schwarzer, G (2016): Hartung-Knapp method is not
always conservative compared with fixed-effect meta-analysis, Statistics
in Medicine, 35, 2503-15
More information about the R-sig-meta-analysis