[R-sig-ME] lmer with binomial distribution of random effects

[Ben Bolker]

El Kihal, Siham <Siham.ElKihal at ...> writes:

> 
> Dear lmer() friends,
> 
> I am trying to estimate a model with a random 
> intercept, and 2 random slopes.
> I believe that my betas (slopes) do not follow 
>a normal distribution, but rather a bimodal distribution.
> The reason for this that there are two possible 
> mechanisms that influence the evolution of this variable,
> one with a negative influence and another one with a
>  positive influence. This is why I need to use a bimodal
> distribution for my slopes to avoid the fact that 
> both effects right now cancel out.
> 
> Does anyone of you has already done this or has 
> an idea how to concretely implement this using lmer()?

  This sounds like a latent mixture model problem.  lme4 doesn't
do this; you *might* be able to implement an expectation-maximization
wrapper around lme4 that would do it, but it wouldn't be entirely
trivial.  If I had to do this I would probably turn to JAGS/BUGS.
Looking forward to other answers from the list ...