[R-meta] P-values one or two-sided

Viechtbauer, Wolfgang (SP) wo||g@ng@v|echtb@uer @end|ng |rom m@@@tr|chtun|ver@|ty@n|
Mon Jun 28 15:40:43 CEST 2021

Dear Tina,

Please see my responses below.


>-----Original Message-----
>From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-project.org] On
>Behalf Of Tina Dudenhöffer
>Sent: Monday, 28 June, 2021 15:32
>To: r-sig-meta-analysis using r-project.org
>Subject: [R-meta] P-values one or two-sided
>Dear all,
>I am working with the Metafor package using the rma.mv function.
>I read that, by default, the p-values are reported for two-sided tests, so I am
>wondering whether I should divide my p-values by two.
>I am asking about the test of moderators specifically (when performing the Q-test
>of Moderation).

The p-value given there is a one-sided p-value (since this is for a chi-square / F-test). There is no need to adjust this p-value.

>Similarly, when removing the intercept (i.e putting a -1 behind the moderator) I
>assume that p-value is not two-sided?

You mean for the QM-test? That's always reported as a one-sided p-value.

>I am just not sure how much of the output is depending on R default and how much
>is part of the Metafor package and how exactly it is set up.
>Thanks for clarifying.
>Kind regards,

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