[R-sig-ME] lmer and log link

[Hugh Sturrock]

Thank you both for your speedy replies. Very helpful.
Hugh




On Oct 31, 2012, at 11:30, David Winsemius <dwinsemius at comcast.net> wrote:

> 
> On Oct 31, 2012, at 11:18 AM, Hugh Sturrock wrote:
> 
>> 
>> Hello all,
>> 
>> 
>> 
>> I am running a lmer model with two random effect levels, household nested in village, with two categorical predictors and a binomial outcome. I would like to obtain risk ratios and so am using the term family=binomial(link=log).
> 
> Couldn't you use Poisson errors with a log link. I would think that should give you risk ratios and be a canonical link-error pairing.
> 
>> However, using this link doesn‚t allow the model to converge properly and I get the following message:
>> 
>> 
>> 
>> Error in
>> mer_finalize(ans) : 
>> 
>> mu[i]
>> must be in the range (0,1): mu = 18.3133, i = 166
>> 
>> 
>> 
>> As I understand it from posts elsewhere, this is due to the fact that one or more observations producing a linear predictor that, when mapped to a predicted probability, falls outside the admissible range of [0,1]. Does anyone know of a way to overcome this?Thank you!Hugh
>> Hugh Sturrock 
>> 
> -- 
> 
> David Winsemius, MD
> Alameda, CA, USA
> 
>