[R-sig-ME] glmer() cluster sample size

[Thierry Onkelinx]

It looks like some subjects were present at multiple locations. The number
of levels is the number of unique combinations of site and subject.

ir. Thierry Onkelinx
Statisticus / Statistician

Vlaamse Overheid / Government of Flanders
INSTITUUT VOOR NATUUR- EN BOSONDERZOEK / RESEARCH INSTITUTE FOR NATURE AND
FOREST
Team Biometrie & Kwaliteitszorg / Team Biometrics & Quality Assurance
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Op vr 31 mrt 2023 om 01:11 schreef Hedyeh Ahmadi <hedyehah using usc.edu>:

> Hello all,
> I'm running a glmer() model with 3 levels where individuals are nested
> within 21 sites and each individual has 1 to 2 repeated measures. My model
> has the random effect structure (1|site/subjet_id).
>
> So I have sample sizes in glmer() output for 3 levels as follows:
> Site=21
> Subject_id:site=9334
> Total number of observations=17592
>
> I was wondering how are these sample sizes calculated in R?
>
> I was under impression that they are just unique number of site,
> subject_id, and total number of rows, for complete cases across all my
> varibles, respectively. This is true for my site and total sample sizes but
> the subject_id:site sample size is confusing me. Shouldn't this just be the
> number of unique subject ids? When I look at number rof unique ids, I get
> 9301 but the glmer() output for subject_id:site is 9334.
>
> Thank you in advance for your time.
>
>
>  Best,
>
>
> Biostatistician​
> Keck School of Medicine
> Department of Preventive Medicine
> University of Southern California
>
> LinkedIn
> www.linkedin.com/in/hedyeh-ahmadi<http://www.linkedin.com/in/hedyeh-ahmadi
> >
>
>
>
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