[R-meta] Can we call moderators in subgroup analysis predictors?

-----Original Message-----
From: Simon Harmel [mailto:sim.harmel at gmail.com]
Sent: Sunday, 20 December, 2020 16:31
To: Viechtbauer, Wolfgang (SP)
Cc: R meta
Subject: Re: [R-meta] Can we call moderators in subgroup analysis
predictors?

Hi Wolfgang,

Thank you very much. To be clear, you're approving of my response, correct?

Best,
Simon

On Sun, Dec 20, 2020 at 6:05 AM Viechtbauer, Wolfgang (SP)
<wolfgang.viechtbauer at maastrichtuniversity.nl> wrote:
I think the reviewer uses the term "meta-analysis" exclusively when pooling
a bunch of effects into a single weighted average. So, to him/her, it does
not make sense to say that there are predictors/moderators/covariates
(whatever you want to call them) in a meta-analysis. If there are predictors
in the model, then the reviewer wants this to be called "meta-regression"
and not "meta-analysis with predictors". I don't think the comment has
anything to do with whether you use the term predictor or moderator.

Best,
Wolfgang

-----Original Message-----
From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces at r-

project.org]

On Behalf Of Simon Harmel
Sent: Sunday, 20 December, 2020 0:39
To: Michael Dewey
Cc: R meta
Subject: Re: [R-meta] Can we call moderators in subgroup analysis
predictors?

Thank you Michael. I had the same reaction. So, this was from a reviewer
who mentioned:

"You say moderators will eventually serve as predictors in a meta-analysis,
are you referring to meta-regression here? Moderators are not used as
predictors in a classic meta-analysis which simply pools all the effects
into a weighted effect size."

My response was:

". . . In both cases, categorical moderators/predictors act as on-and-off
switches. I always prefer the meta-regression as it reveals the partial
effect of one moderator controlling for other moderators. But again, in my
context it is fine to generally use the term predictor. I think some may
even find the term moderator confusing because in general it may denote
some kind of interactional effect".

Just wanted to make sure I'm not too far off.

Thanks,
Simon

On Sat, Dec 19, 2020 at 4:32 AM Michael Dewey <lists at dewey.myzen.co.uk>
wrote:

Dear Simon

My immediate thought is, "Yes, why not?" but do you have some deep doubt
you want to share with us?

Michael

On 18/12/2020 22:51, Simon Harmel wrote:

For clarification, I'm only concerned with categorical moderators.

Thanks again,
Simon

On Fri, Dec 18, 2020 at 3:33 PM Simon Harmel <sim.harmel at gmail.com>

wrote:

Hello All,

A quick question. In classic meta-analysis, moderators help to form

groups

of studies and conduct meta analysis separately in each group.

In meta-regression, moderators are directly predictors of effect size

in a

regression analysis.

But, can we still call moderators in classic meta-analysis predictors

of

effect size?

Thank you,
Simon