[R] nlme::lme sigma parameter standard deviation or variance?

Eric Berger er|cjberger @end|ng |rom gm@||@com
Sat Dec 18 11:00:25 CET 2021

You can run a test. Multiply all your data by a scalar, say 2.
If this changes the result lme_mod$sigma by a factor of 2, then it is
a std deviation.
If it changes the result by a factor of 4, then it is a variance.


On Sat, Dec 18, 2021 at 11:26 AM Courtney Van Den elzen
<Courtney.VanDenelzen using colorado.edu> wrote:
> Hi R-help,
> I am a researcher fitting linear mixed models using the package nlme. I am
> wondering whether the sigma value that is outputted as part of the model
> object is standard deviation or variance? for example, I might fit a model
> lme_mod <- nlme::lme(response ~ predictor1 + predictor2, random =
> (~1|grouping1))
> I am wondering whether lme_mod$sigma is actually a standard deviation or if
> it's a variance.
> Thanks so much,
> Courtney
>         [[alternative HTML version deleted]]
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