[R-meta] compare multiple "bayesmeta" estimates

Röver, Christian chr|@t|@n@roever @end|ng |rom med@un|-goett|ngen@de
Sun Dec 27 13:00:29 CET 2020


Dear Simon,

yes, there is a way to investigate the difference of the two as well.
Asking for the difference between the two unknowns (the two mean
parameters) technically means asking for a *convolution* of their
probability distributions. From the "bayesmeta()" output we get the
probability density functions etc, and from these we can derive the
convolution. A method to compute the convolution is described here:

  C. Roever and T. Friede.
  Discrete approximation of a mixture distribution 
  via restricted divergence.
  Journal of Computational and Graphical Statistics, 
  26(1):217-222, 2017.
  https://doi.org/10.1080/10618600.2016.1276840 

and R code is provided in the article's supplemental material.

I attached some R code to show the computations based on the "metafor"
example.

Cheers,

Christian



On Sat, 2020-12-26 at 13:49 -0600, Simon Harmel wrote:
> Dear Christian,
> 
> Thank you very much. To be clear, you're suggesting a meta-analysis
> of the subgroup meta-analyses, correct?
> 
> Well, in my case, I have way too many subgroups, so there will be
> many pairwise comparisons. I wonder if there is a way to get the
> large posterior samples from each subgroup' summary effect and
> subtract it from the large posterior samples from another subgroup 
> summary effect etc.?
> 
> Perhaps, then we can see if the HDI of the posterior of difference
> includes "0"?
> 
> Is this possible and/or reasonable given that my goal is to see if
> one subgroup is "different" from another one or not?
> 
> Thank you,
> Simon
> 
> On Sat, Dec 26, 2020 at 12:38 PM Röver, Christian <
> christian.roever using med.uni-goettingen.de> wrote:
> > Dear Simon,
> > 
> > you can essentially do an analogous analysis (in two stages) using
> > the
> > "bayesmeta" package. Doing the one-stage meta-regression approach
> > is
> > not (yet) possible with bayesmeta, but it should be possible via
> > "rjags" (of required).
> > 
> > For the two-stage approach, we then only need to use a normal
> > approximation for the results from the 1st-stage analyses and
> > proceed
> > from there.
> > 
> > I attached some example R code based on the quoted "metafor"
> > example.
> > 
> > Cheers,
> > 
> > Christian
> > 
> > 
> > 
> > On Sat, 2020-12-26 at 10:46 -0600, Simon Harmel wrote:
> > > Hello All,
> > > 
> > > Using "bayesmeta" package, I want to compare multiple estimates
> > of
> > > independent Meta-Analyses (i.e., Subgroups).
> > > 
> > > In metafor, I know we can do this: (
> > > 
> > http://www.metafor-project.org/doku.php/tips:comp_two_independent_estimates
> > > )
> > > 
> > > But I have fit my models in the "bayesmeta" package, so I was
> > > wondering how to compare across my "bayesmeta" models?
> > > 
> > > Thanks,
> > > Simon
> > > 
> > > 

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