[R-meta] Meta - Bug with REML or small N?

[Viechtbauer, Wolfgang (NP)]

Hi Jorge,

Could you do

dput(dat_vo2)

and paste the resulting code here?

Best,
Wolfgang

From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-project.org] On Behalf Of Jorge Teixeira via R-sig-meta-analysis
Sent: Tuesday, 21 March, 2023 15:57
To: R meta
Cc: Jorge Teixeira
Subject: [R-meta] Meta - Bug with REML or small N?

Hi.

Let me know if you need me to provide the data for this example. Screenshots in the bottom.

I ran this MA with REML, and the weight for random and common effects are exactly the same! Never saw anything like this.  t2 values also don’t look plausible. 

#1
vo2 <- metacont(en  , em, esd, cn, cm, csd, study, method.tau = "REML", prediction = TRUE, data = dat_vo2, sm = "MD")
vo2

Is this a bug or a particular issue of low number of studies and low sample size?

#2
vo2 <- metacont(en  , em, esd, cn, cm, csd, study, method.tau = "DL", prediction = TRUE, data = dat_vo2, sm = "MD")
vo2

I ran this with DL estimator and weights and t2 are plausible. I also ran other similar MA using REML and this was all okay. 

#1 using SMD instead of MD also looks fine.

Thanks,
Jorge

REML:

DL: