34,822 research outputs found

    Estimating the Distribution of Dietary Consumption Patterns

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    In the United States the preferred method of obtaining dietary intake data is the 24-hour dietary recall, yet the measure of most interest is usual or long-term average daily intake, which is impossible to measure. Thus, usual dietary intake is assessed with considerable measurement error. We were interested in estimating the population distribution of the Healthy Eating Index-2005 (HEI-2005), a multi-component dietary quality index involving ratios of interrelated dietary components to energy, among children aged 2-8 in the United States, using a national survey and incorporating survey weights. We developed a highly nonlinear, multivariate zero-inflated data model with measurement error to address this question. Standard nonlinear mixed model software such as SAS NLMIXED cannot handle this problem. We found that taking a Bayesian approach, and using MCMC, resolved the computational issues and doing so enabled us to provide a realistic distribution estimate for the HEI-2005 total score. While our computation and thinking in solving this problem was Bayesian, we relied on the well-known close relationship between Bayesian posterior means and maximum likelihood, the latter not computationally feasible, and thus were able to develop standard errors using balanced repeated replication, a survey-sampling approach.Comment: Published in at http://dx.doi.org/10.1214/12-STS413 the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org). arXiv admin note: substantial text overlap with arXiv:1107.486

    QMC and the nature of dense matter: written in the stars?

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    We discuss the recent progress in calculating the properties of 'hybrid stars' (stellar objects similar to neutron stars, classified by the incorporation of non-nucleonic degrees of freedom, including but not limited to hyperons and/or a quark-matter core) using the octet-baryon Quark-Meson Coupling (QMC) model. The version of QMC used is a recent improvement which includes the in-medium modification of the quark-quark hyperfine interaction.Comment: 6 pages, 2 figures. To appear in the proceedings of Achievements and New Directions in Subatomic Physics: Workshop in Honour of Tony Thomas' 60th Birthday, Adelaide, South Australia, 15-19 Feb 201


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    Agricultural and Food Policy,