[R-meta] Removing the intercept in rma.mv after non-significant QM/F test

Viechtbauer, Wolfgang (SP) wo||g@ng@v|echtb@uer @end|ng |rom m@@@tr|chtun|ver@|ty@n|
Thu Dec 9 18:09:15 CET 2021


@Tina: Also see this write-up:



>-----Original Message-----
>From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-project.org] On
>Behalf Of Michael Dewey
>Sent: Thursday, 09 December, 2021 16:59
>To: T D; r-sig-meta-analysis using r-project.org
>Subject: Re: [R-meta] Removing the intercept in rma.mv after non-significant QM/F
>Dear Tina
>When you leave the intercept in you are testing whether the two levels
>differ. When you take it out you are separately testing for each whether
>its coefficient differs from zero. Those are clearly not the same.
>On 09/12/2021 12:32, T D wrote:
>> Dear all,
>> I have a question regarding the rma.mv function.
>> Some QM tests (test of moderation) are not significant. However, I continued to
>investigate both levels of the moderator regardless by removing the intercept
>(i.e with placing a -1 at the end)
>> How sensible is this and what kind of conclusions can I draw when both levels
>(after removing the intercept) produce significant results. I understand I can’t
>draw any overall conclusions for the a priori hypotheses, considering the test of
>moderation was not significant - but generally, I wonder, whether it is “ok” to
>report this - or whether it is simply wrong to continue with any analysis if the
>QM test is not significant.
>> Many thanks for clarifying.
>> Kind regards,
>> Tina Dudenhöffer

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