[R-meta] How to Get PIs for Moderator Analyses

Michael Dewey ||@t@ @end|ng |rom dewey@myzen@co@uk
Thu Jun 15 18:18:17 CEST 2023

Dear Tori

Just to clarify the reasoning behind my comments I was concerned that 
your data may not be adequate to fit the model since you seemed to have 
very small random variances and little effect from the moderators.


On 14/06/2023 10:22, Viechtbauer, Wolfgang (NP) via R-sig-meta-analysis 
> Michael means using the profile() function.
> This aside, if you use predict(<model>), then it will compute predicted/fitted values based on the model matrix (and corresponding CIs/PIs). If you want predicted values for particular combinations of moderator values, then you have to specify the 'newmods' argument.
> Best,
> Wolfgang
>> -----Original Message-----
>> From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-project.org] On
>> Behalf Of Tori Peña via R-sig-meta-analysis
>> Sent: Tuesday, 13 June, 2023 19:51
>> To: Michael Dewey
>> Cc: Tori Peña; R Special Interest Group for Meta-Analysis
>> Subject: Re: [R-meta] How to Get PIs for Moderator Analyses
>> Hi Michael,
>> Thanks for your response!  What do you mean by profiling the variance?
>> Yes, some of my moderators had virtually no effect in our models.  I have
>> the issue with the PI being displayed for each data point in the model
>> instead of the PI for the model across all the moderators, unfortunately.
>> On Tue, Jun 6, 2023 at 12:20 PM Michael Dewey <lists using dewey.myzen.co.uk>
>> wrote:
>>> Dear Tori
>>> It might help to know exactly why you think the ouput is incorrect but I
>>> notice that (a) your random effects seem to have very small variances
>>> (have you tried profiling them?) (b) your moderator does not seem to
>>> have much effect either.
>>> Michael
>>> On 06/06/2023 16:59, Tori Peña via R-sig-meta-analysis wrote:
>>>> Hello Listserv -
>>>> I wanted to know if folks know of a way to get prediction intervals for
>>>> moderator analyses!  I tried the predict() function but the output looks
>>>> incorrect.  I attached a screenshot below of the code plus a part of the
>>>> output.
>>>> Thanks in advance!
>>>> --
>>>> *Tori Peña, Ph.D. *(she/her/ella)
>>>> Cognitive Psychology
>>>> Dept. of Psychology
>>>> Stony Brook University
>>>> Stony Brook, NY 11790-2500
>>>> Stony Brook University logo
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