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This is the preliminary program for the 2009 Joint Statistical Meetings in Washington, DC.

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Activity Number: 537
Type: Invited
Date/Time: Thursday, August 6, 2009 : 8:30 AM to 10:20 AM
Sponsor: Biopharmaceutical Section
Abstract - #303180
Title: Computational Methods for Nonlinear Mixed Models
Author(s): Douglas M. Bates*+
Companies: University of Wisconsin-Madison
Address: 1300 University Ave, Statistics Dept, Madison, WI, 53706,
Keywords: mixed-effects ; pharmacokinetics ; lme4
Abstract:

Population pharmacokinetics data are often modeled using nonlinear mixed-effects models; nonlinear because the pharmacokinetic parameters---rate constants, clearance rates, etc.---occur nonlinearly in the model function and mixed-effects because the models involve both fixed-effects parameters, applying to the population or well-defined subsets of the population, and random effects associated with particular experimental or observational units under study. Many algorithms for estimating the parameters in such models have been proposed and implemented but often the estimation algorithm is confused with the parameter estimation criterion - maximum likelihood. I suggest we concentrate on evaluating or approximating the log-likelihood to be optimized and will describe how this is done in the nlmer function in the lme4 package for R.


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