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

Viechtbauer, Wolfgang (SP) wo||g@ng@v|echtb@uer @end|ng |rom m@@@tr|chtun|ver@|ty@n|
Mon Jan 4 23:19:32 CET 2021

Dear Simon,

Not really. Your response is focused on a different issue.


>-----Original Message-----
>From: Simon Harmel [mailto:sim.harmel using 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
>Hi Wolfgang,
>Thank you very much. To be clear, you're approving of my response, correct?
>On Sun, Dec 20, 2020 at 6:05 AM Viechtbauer, Wolfgang (SP)
><wolfgang.viechtbauer using 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.
>>-----Original Message-----
>>From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-
>>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
>>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.
>>On Sat, Dec 19, 2020 at 4:32 AM Michael Dewey <lists using dewey.myzen.co.uk>
>>> 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 using 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
>>> >> effect size?
>>> >>
>>> >> Thank you,
>>> >> Simon

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