Dear Jorge
It looks as though the issue is that REML estimates tau^2 to be
effectively zero whereas DL has a positive estimate. The different ways
of estimating tau^2 do often differ, sometimes by quite surprising
amounts. Whether that is related to the smallish number of studies I
could not say but, at the moment, there does not seem to be evicence of
anything wrong with the implementation of REML.
Michael
On 21/03/2023 14:57, Jorge Teixeira via R-sig-meta-analysis wrote:
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. t2values 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 t2are 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:_*
image.png
*_DL:_*
image.png
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