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

Fri, Jun 23, 2023 4:53 AM

Dear Tori,

The profile() function is not for getting PIs. You are misunderstanding what Michael was suggesting -- he was suggesting to use profile() to check if the variance components are identifiable by examining the profile likelihood plots. And predict() works just fine for getting PIs. Like I wrote, you have to use the 'newmods' argument in predict() to specify for which combination of moderator values you want to obtain a predicted effects (and the corresponding CI and PI).

Best,
Wolfgang

-----Original Message-----
From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces at r-project.org] On
Behalf Of Tori Pe?a via R-sig-meta-analysis
Sent: Thursday, 22 June, 2023 19:37
To: R Special Interest Group for Meta-Analysis
Cc: Tori Pe?a
Subject: Re: [R-meta] How to Get PIs for Moderator Analyses

Thanks, all!

Unfortunately, the profile() function did not yield PIs for our moderator
analyses.  Are there other ways to get the PIs for rma.mv models since
predict() and profile() are not working?

On Thu, Jun 15, 2023 at 12:18?PM Michael Dewey via R-sig-meta-analysis <
r-sig-meta-analysis at r-project.org> wrote:

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 at r-project.org] On

Behalf Of Tori Pe?a via R-sig-meta-analysis
Sent: Tuesday, 13 June, 2023 19:51
To: Michael Dewey
Cc: Tori Pe?a; 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 at dewey.myzen.co.uk>
wrote:

Dear Tori

It might help to know exactly why you think the ouput is incorrect but

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 Pe?a 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 Pe?a, Ph.D. *(she/her/ella)
Cognitive Psychology
Dept. of Psychology
Stony Brook University
Stony Brook, NY 11790-2500
Stony Brook University logo

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

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