R help - Jan 2011 - Greetings. I have a question with mixed beta regression model in nlme (corrected version).

*Dear R-help:

My name is Rodrigo and I have a question with nlme package
in R to fit a mixed beta regression model. I'm so sorry. In the last
email, I forgot to say that W is also a unknown parameter in the mixed
beta regression model. In any case, here I send you the correct formulation.
**

Suppose that:*

*j in {1, ..., J}* *(level 1)*
*i in {1, ..., n_j}* *(level 2)*

*y_{ij} ~ Beta(mu_{ij} * phi_{ij}; (1 - mu_{ij}) * phi_{ij})

y_{ij} = mu_{ij} + w_{ij}
*
*with*

*logit(mu_{ij}) = Beta_{0i} + Beta_{1i} * x1_{ij} + b_2 * x2_{ij}
log(phi_{ij}) = Gamma_{0i} + Gamma_{1i} * z1_{ij} + c_2 * z2_{ij}
*
*Beta_{0i} = b_0 + u_{0i}
Beta_{1i} = b_1 + u_{1i}
Gamma_{0i} = c_0 + v_{0i}
Gamma_{1i} = c_1 + v_{1i}
*
*The vector* *(u_{0i}, u_{1i})'* *has normal distribution with mean*
*(0, 0)'* *and covariance matrix*

*sigma_{00} sigma_{01}
sigma_{10} sigma_{11}
*
*The vector* *(v_{0i}, v_{1i})'* *has normal distribution with mean*
*(0, 0)'* *and covariance matrix*

*delta_{00} delta_{01}
delta_{10} delta_{11}
*
*The* *w_{ij}s are independents. Each* *w_{ij}* *has mean* *0* *and variance
* *W*.

*The unknown parameters are:*
*
b_0, b_1, b_2, c_0, c_1, c_2, sigma_{00}, sigma_{10},
sigma_{11}, delta_{00}, delta_{10}, **delta_{11}** **and* *W*.

*The question is:
How can I use nlme package in R to fit this model?
If you want to know additional information, send me a mail, please.

In advance, thanks a lot for your help.

Kind regards,
Rodrigo.*

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