[R-sig-ME] Very small random effect estimation in lmer but not in stata xtmixed

[Ben Bolker]

Mohammed Mohammed <M.A.MOHAMMED at ...> writes:


> I am using the lmer function (in the lme4 library) to analyse some
> data where individuals are clustered into sets (using the SetID
> variable) with a single fixed effect (cc - 0 or 1). The lmer model
> and output is shown below.



> Whilst the fixed effects are consistent with stata (using xtmixed,
> see below), the std dev of the random effect for SetID is very very
> small (3.5803e-05)compared to stata's (see below 1.002). Any ideas
> why this should be happening please....?

> I am happy to share my data if that helps.
> 

  Nothing really obvious pops out.  Have you tried
nlme (i.e library(nlme); lme(AnxietyScore ~cc, random=~1|SetID,data=mydf))
as a cross-check?

  Can you send/post data?

  Ben Bolker