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

[Viechtbauer, Wolfgang (NP)]

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