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The International Journal of Biostatistics

Ed. by Hubbard, Alan E. / van der Laan, Mark J.

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Fitting a Bivariate Measurement Error Model for Episodically Consumed Dietary Components

Saijuan Zhang1 / Susan M. Krebs-Smith2 / Douglas Midthune3 / Adriana Perez4 / Dennis W. Buckman5 / Victor Kipnis6 / Laurence S. Freedman7 / Kevin W. Dodd8 / Raymond J Carroll9

1Texas A&M University

2National Cancer Institute

3National Cancer Institute

4University of Texas School of Public Health

5Information Management Services, Inc.

6National Cancer Institute

7Gertner Institute for Epidemiology and Public Health Research

8National Cancer Institute

9Texas A&M University

Citation Information: The International Journal of Biostatistics. Volume 7, Issue 1, Pages 1–32, ISSN (Online) 1557-4679, DOI: 10.2202/1557-4679.1267, January 2011

Publication History:
Published Online:
2011-01-06

There has been great public health interest in estimating usual, i.e., long-term average, intake of episodically consumed dietary components that are not consumed daily by everyone, e.g., fish, red meat and whole grains. Short-term measurements of episodically consumed dietary components have zero-inflated skewed distributions. So-called two-part models have been developed for such data in order to correct for measurement error due to within-person variation and to estimate the distribution of usual intake of the dietary component in the univariate case. However, there is arguably much greater public health interest in the usual intake of an episodically consumed dietary component adjusted for energy (caloric) intake, e.g., ounces of whole grains per 1000 kilo-calories, which reflects usual dietary composition and adjusts for different total amounts of caloric intake. Because of this public health interest, it is important to have models to fit such data, and it is important that the model-fitting methods can be applied to all episodically consumed dietary components.

We have recently developed a nonlinear mixed effects model (Kipnis, et al., 2010), and have fit it by maximum likelihood using nonlinear mixed effects programs and methodology (the SAS NLMIXED procedure). Maximum likelihood fitting of such a nonlinear mixed model is generally slow because of 3-dimensional adaptive Gaussian quadrature, and there are times when the programs either fail to converge or converge to models with a singular covariance matrix. For these reasons, we develop a Monte-Carlo (MCMC) computation of fitting this model, which allows for both frequentist and Bayesian inference. There are technical challenges to developing this solution because one of the covariance matrices in the model is patterned. Our main application is to the National Institutes of Health (NIH)-AARP Diet and Health Study, where we illustrate our methods for modeling the energy-adjusted usual intake of fish and whole grains. We demonstrate numerically that our methods lead to increased speed of computation, converge to reasonable solutions, and have the flexibility to be used in either a frequentist or a Bayesian manner.

Keywords: Bayesian approach; latent variables; measurement error; mixed effects models; nutritional epidemiology; zero-inflated data

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