[R] Add prediction interval forest plot (package "meta")

Bernd Weiß bernd.weiss at uni-koeln.de
Fri Jun 7 13:39:39 CEST 2013

Am 07.06.2013 13:17, schrieb Michael Dewey:
> At 19:34 06/06/2013, Bernd Weiss wrote:
>> Dear all,
>> I am struggling to add a prediction interval to a forest plot that was
>> created with forest.meta(), package "meta".
>> I checked the source of forest.meta() and realized that it is heavily
>> relying on grid. I am lacking any experience with grid graphics. So, I
>> am having difficulties to find out where the random effects estimate is
>> actually plotted in order to add prediction intervals.
> I appreciate this is not a direct answer to your question but the
> equivalent function in metafor (available from CRAN) does this and it
> might be easier to use that.

Thanks, Michael!

Yes, I vaguely remember that the metafor package can calculate the PIs 
but most of our analyses rely on the meta package. On the other hand, 
this might be a good reason to finally switch to metafor.

You probably refer to the function addpoly() which can be used for that. 
I will check it out.

Again, thanks for your help,


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