Message-ID: <BLU0-SMTP67398693EF37E3117C17A2C8600@phx.gbl>
Date: 2012-11-01T14:46:05Z
From: Hugh Sturrock
Subject: lmer and log link
In-Reply-To: <662DABE0-CA3A-4A43-8FE2-3E52AECCA0BD@comcast.net>
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
>
>