Re: [R] need help on nlme()

From: ronggui <ronggui.huang_at_gmail.com>
Date: Mon 20 Feb 2006 - 20:53:53 EST

I think nlme is not for logistic mixed effect model. you should use glmmPQL in MASS or lmer in Matrix

2006/2/20, Mingyu Feng <mingyufeng@gmail.com>:
> Hello there,
>
> I am using nlme() to fit a logistic mixed effect model on our data.
> The outcome variable is binary.
> I got the error when I wanted to add a group factor to my model.
>
> My initial model is as below:
>
> model.a <- nlme(response~ 1/(1 + exp( -intercept- u0 - slope*TIME -
> u1*TIME)),
> + fixed=intercept+slope~1, random= u0+u1~1
> |studentID,
> + start=c(slope=.01, intercept=-1), data=log.data,
> method='ML')
>
> This works fine on my data. But when i update it by adding a group factor
> SKILLS,
> I got the error message:
> "Error in nlme.formula(response ~ 1/(1 + exp( -intercept- u0 - slope*TIME
> :
> starting values for the fixed component are not the correct length"
>
> The model is as below:
> model.a <- nlme(response~ 1/(1 + exp( -intercept- u0 - slope*TIME -
> u1*TIME)),
> + fixed=intercept+slope ~ SKILLS, random= u0+u1~1
> |studentID,
> + start=c(slope=.01, intercept=-1), data=log.data,
> method='ML')
>
> Does anybody see anything wrong with the "start" part of this model?
>
> Thanks a lot!!
>
> [[alternative HTML version deleted]]
>
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--
ٹ
Deparment of Sociology
Fudan University



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Received on Mon Feb 20 20:59:03 2006

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