Re: [R] Glmm for multiple outcomes

From: Spencer Graves <spencer.graves_at_pdf.com>
Date: Mon 10 Oct 2005 - 02:05:03 EST

Does the following help:

n.subjects <- 3
J <- 4
K <- 5
n.ijk <- rep(2, each=n.subjects*J*K)

x <- rep(1:K, n.subjects, each=J)

subj <- factor(rep(1:n.subjects, each=K*J))

sa.subject <- 1
sb.subject <- 1

set.seed(2)
a.subj <- rep(sa.subject*rnorm(n.subjects), each=K*J) b.subj <- rep(sb.subject*rnorm(n.subjects), each=K*J)

Z <- a.subj+b.subj*x

library(boot)
Y <- (rbinom(n.subjects*K*J, n.ijk, inv.logit(Z))

          /n.ijk)

Dat <- data.frame(subj=subj, x=x, y=Y)

library(lme4)

fit <- lmer(y~x+(x|subj), Dat)
Linear mixed-effects model fit by REML
Formula: y ~ x + (x | subj)

    Data: Dat

       AIC      BIC    logLik MLdeviance REMLdeviance
  51.63172 64.19779 -19.81586    33.1066     39.63172
Random effects:
  Groups   Name        Variance  Std.Dev. Corr
  subj     (Intercept) 0.0446346 0.211269
           x           0.0032613 0.057108 1.000
  Residual             0.0879438 0.296553
# of obs: 60, groups: subj, 3

Fixed effects:

              Estimate Std. Error DF t value Pr(>|t|) (Intercept) 0.350000 0.151459 58 2.3109 0.02442 * x 0.033333 0.042661 58 0.7814 0.43777

---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

	  spencer graves

Abderrahim Oulhaj wrote:


> Dear All,
>
> I wonder if there is an efficient way to fit the generalized linear mixed model for multivariate outcomes.
>
> More specifically, Suppose that for a given subject i and at a given time j we observe a multivariate outcome Yij = (Y_ij1, Y_ij2, ..., Y_ijK).
> where Y_ijk is a binomial(n_ijk, p_ijk).
>
> One way to jointly model the data is to use the following specification:
>
> g(p_ijk) = beta_0k + b_0ik + (beta_1k + b_1ik)*x_ijk with k = 1,2 ...., K , g is a specified link function and (b_0ik,b_1ik) k=1,...K are random effects ...
>
> I my case, the glmmPQL converges only and give good results when k is less than 3 (i.e. for a small number of random effects). I also used the gee (generalized estimating equations) to estimate the fixed effects and the same probleme ariseed with k.
>
> Is there any help?
>
> Thank you in advance,
>
> Abderrahim Oulhaj
> [[alternative HTML version deleted]]
>
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-- Spencer Graves, PhD Senior Development Engineer PDF Solutions, Inc. 333 West San Carlos Street Suite 700 San Jose, CA 95110, USA spencer.graves@pdf.com www.pdf.com <http://www.pdf.com> Tel: 408-938-4420 Fax: 408-280-7915 ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Received on Mon Oct 10 02:11:40 2005

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