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

[Michael Dewey]

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.

Michael

On 14/06/2023 10:22, Viechtbauer, Wolfgang (NP) via R-sig-meta-analysis 
wrote:
> 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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-- 
Michael
http://www.dewey.myzen.co.uk/home.html