Bayesian estimation for percolation models of disease spread in plant populations

Statistical methods are formulated for fitting and testing percolation-based, spatio-temporal models that are generally applicable to biological or physical processes that evolve in spatially distributed populations. The approach is developed and illustrated in the context of the spread of Rhizoctonia solani, a fungal pathogen, in radish but is readily generalized to other scenarios. The particular model considered represents processes of primary and secondary infection between nearest-neighbour hosts in a lattice, and time-varying susceptibility of the hosts. Bayesian methods for fitting the model to observations of disease spread through space and time in replicate populations are developed. These use Markov chain Monte Carlo methods to overcome the problems associated with partial observation of the process. We also consider how model testing can be achieved by embedding classical methods within the Bayesian analysis. In particular we show how a residual process, with known sampling distribution, can be defined. Model fit is then examined by generating samples from the posterior distribution of the residual process, to which a classical test for consistency with the known distribution is applied, enabling the posterior distribution of the P-value of the test used to be estimated. For the Rhizoctonia-radish system the methods confirm the findings of earlier non-spatial analyses regarding the dynamics of disease transmission and yield new evidence of environmental heterogeneity in the replicate experiments.     

Behavioral health service use and costs among children in foster care

This article compares behavioral health service use and cost for foster care versus nonfoster care children; children before, during, and after foster care placement; and successfully reunified versus nonsuccessfully reunified foster care children. Behavioral health service costs for children in foster care were higher than for children not in foster care. Children in foster care used more services during their foster care placement than before placement and after discharge. Nonsuccessfully reunified children received a significantly larger quantity of services than those successfully reunified.     

Designing for diversity: incorporating cultural competence in prevention programs for urban youth

Low-income urban youth of color frequently confront a wide variety of challenges and hardships that other young people never experience. The offering of prevention programs represents one strategy to help urban youth avoid the risks associated with substance abuse. In this chapter, an alternative program strategy is posited-one that places diversity with respect to culture, class, and environment at the center of prevention efforts. Such an approach, the authors argue, is more effective not only in appealing to the sensibilities of urban youth but also in altering their behavior.     

Dealing with excess of zeros in the statistical analysis of magnetic resonance imaging lesion count in multiple sclerosis

Lesion count observed on brain magnetic resonance imaging scan is a common end point in phase 2 clinical trials evaluating therapeutic treatment in relapsing remitting multiple sclerosis (MS). This paper compares the performances of Poisson, zero‐inflated poisson (ZIP), negative binomial (NB), and zero‐inflated NB (ZINB) mixed‐effects regression models in fitting lesion count data in a clinical trial evaluating the efficacy and safety of fingolimod in comparison with placebo, in MS. The NB and ZINB models prove to be superior to the Poisson and ZIP models. We discuss the advantages and limitations of zero‐inflated models in the context of MS treatment. Copyright © 2012 John Wiley & Sons, Ltd.     

From the new left to the new enlightenment: the methodological implications of public attention on private lives

Research on Rajneeshpuram was partially supported by the Center for the Study of Women in Society and a Summer Research Grant from University of Oregon. Research on the fate of Santa Barbara activists was partially supported by grants from the Society for the Psychological Study of Social Issues and the Graduate Division of the University of California at Santa Barbara.     

Servers and providers: the distribution of food within the family*

We examine the nature of decision-making surrounding food provision within families and the patterns of food distribution established. The analysis draws upon detailed interview material and dairy records gather from 200 women currently bringing up young children. The sexual divisions and power relations which characterize families are found to have an impact on the choice of food for family consumption and on women's theories concerning the food needs of family members. The manner in which these theories are given concrete expression in the differential distribution of meat both between the sexes and intergenerationally is revealed. Variations in the extent of such inequalities are assessed with reference to the nature of the work undertaken by the marital partners and their relative control over money.