[R-meta] Negative values of df in test of moderators using robust()

[Viechtbauer, Wolfgang (NP)]

Dear Sebastian,

Yes, I assume that this is the issue. Here is a reproducible example to illustrate this:

library(metafor)
dat <- dat.konstantopoulos2011
res <- rma.mv(yi, vi, random = ~ 1 | district/school, data=dat, mods = ~ 0 + factor(year))
robust(res, cluster=district, clubSandwich=TRUE)

CC-ing James, since this is really coming from clubSandwich.

Best,
Wolfgang

>-----Original Message-----
>From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-project.org] On
>Behalf Of Röhl, Sebastian
>Sent: Tuesday, 31 January, 2023 11:49
>To: r-sig-meta-analysis using r-project.org
>Subject: [R-meta] Negative values of df in test of moderators using robust()
>
>Dear all,
>
>I have a question regarding robust(): I'm using robust with clubSandwich-option
>for testing moderator effects.
>In the test of moderators, a negative df2-value appears:
>Test of Moderators (coefficients 1:8):
>F(df1 = 8, df2 = -2.68) = 0.0000, p-val = NA
>
>In the standard output (without CRVE):
>
>Test of Moderators (coefficients 1:8):
>
>QM(df = 8) = 10.0880, p-val = 0.2589
>
>How could I interpret this phenomen? Could this happen due to small numbers of ES
>for some of the moderators?
>
>Thank you for your help!
>Best,
>Sebastian
>
>****************************
>Dr. Sebastian R�hl
>Eberhard Karls Universit�t T�bingen
>Institute for Educational Science
>T�bingen School of Education (T�SE)
>Wilhelmstra�e 31 / Room 302
>D-72074 T�bingen
>Germany
>
>Phone: +49 7071 29-75527
>Fax: +49 7071 29-35309
>Email: sebastian.roehl using uni-tuebingen.de<mailto:sebastian.roehl using uni-tuebingen.de>
>Twitter: @sebastian_roehl  @ResTeacherEdu