Predictive control of posterior robustness for sample size choice in a Bernoulli model

In this article we consider the sample size determination problem in the context of robust Bayesian parameter estimation of the Bernoulli model. Following a robust approach, we consider classes of conjugate Beta prior distributions for the unknown parameter. We assume that inference is robust if posterior quantities of interest (such as point estimates and limits of credible intervals) do not change too much as the prior varies in the selected classes of priors. For the sample size problem, we consider criteria based on predictive distributions of lower bound, upper bound and range of the posterior quantity of interest. The sample size is selected so that, before observing the data, one is confident to observe a small value for the posterior range and, depending on design goals, a large (small) value of the lower (upper) bound of the quantity of interest. We also discuss relationships with and comparison to non robust and non informative Bayesian methods.     

A simple approximation relation between the symmetric generalized logistic and the students t distributions

In this paper, we obtain a new approximation of the Student's t distribution by using the symmetric generalized logistic (SGL) distribution function. The error of this approximation is shown to be 0(1/n² )where nis the degrees of freedom of thetdistribution. In comparison to similar approximations by George and Ojo and George et al. (1986), this new approximation is much simpler and more accurate. It is also shown that under some conditions, the tdistribution is a good approximation of the SGL distribution. Therefore, the complicated expressions for the cumulants and moments of the SGL can be approximated by those of the t, distribution. Finally, numerical results are given.     

Modern Food Supply Chains and Development: Evidence from Horticulture Export Sectors in Sub‐Saharan Africa

The global food system is undergoing rapid processes of transformation and modernisation. This is causing important changes in developing‐country food supply chains, particularly in supermarket‐driven and high‐value export chains, but the welfare implications of these changes are poorly understood. This article analyses and compares the welfare effects in different horticulture export chains in sub‐Saharan Africa, disentangling different types of effects and the channels through which rural households are affected. Its main conclusion is that increased high‐value exports and the modernisation of export supply chains can bring about important positive welfare effects, which can occur in various ways through product‐ or labour‐market effects and through direct and indirect effects.     

新世纪的课题：党的领导方式的创新与建构

面对新世纪党的执政环境和执政使命 ,传统的党的领导方式面临挑战。创新和建构民主法治型的领导方式 ,是发展市场经济、推进民主政治和依法治国、巩固党的执政地位、深化政治体制改革的必然要求     

对我国公有制理论的实践与发展问题的思考

十一届三中全会以前,我国在社会主义建设过程中,对公有制理论进行了初步探索,但是这种探索是很不成功的.十一届三中全会以后,我国对公有制实现形式进行了多方面的再探索并取得了重大成就.党的十五大在总结历史经验的基础上,实现了公有制理论的重大突破,从而找到了一套与我国基本国情相适合的公有制理论.     

Double-sampling control charts for attributes

In this article, we propose a double-sampling (DS) np control chart. We assume that the time interval between samples is fixed. The choice of the design parameters of the proposed chart and also comparisons between charts are based on statistical properties, such as the average number of samples until a signal. The optimal design parameters of the proposed control chart are obtained. During the optimization procedure, constraints are imposed on the in-control average sample size and on the in-control average run length. In this way, required statistical properties can be assured. Varying some input parameters, the proposed DS np chart is compared with the single-sampling np chart, variable sample size np chart, CUSUM np and EWMA np charts. The comparisons are carried out considering the optimal design for each chart. For the ranges of parameters considered, the DS scheme is the fastest one for the detection of increases of 100% or more in the fraction non-conforming and, moreover, the DS np chart is easy to operate.     

Crossing probabilities for a square root boundary by a bessel process

Probabilities for Wiener and Bessel processes to cross a square root boundary are calculated and the Mellin transform of the distribution of the associated stopping time is given.The transform is inverted and a table of critical values for the crossing probability as a function of the observation time is included. Also an analytic expression for the crossing probability is computed for the case of constant drift.     

Green Care Farms Promote Activity Among Elderly People With Dementia

In the Netherlands, an increasing number of green care farms are providing day care to community-dwelling elderly people with dementia. Currently, it is unknown whether activities, activity participation, and facility use of elderly people with dementia at green care farms differ from those at regular day care facilities. The authors performed group and individual observations at 11 green care farms and 12 regular day care facilities. Activities of elderly people at green care farms were more frequent, occurred outdoors more often, were of a higher physical intensity, and more often were aimed at individuals than activities at regular day care facilities. Therefore, the green care farms’ environment may be more beneficial for elderly people with dementia than the regular day care facility environment.     

Understanding the Positive Effects of Graphical Risk Information on Comprehension: Measuring Attention Directed to Written,Tabular, and Graphical Risk Information

Risk communications are an integral aspect of health education and promotion. However, the commonly used textual risk information is relatively difficult to understand for the average recipient. Consequently, researchers and health promoters have started to focus on so‐called decision aids, such as tables and graphs. Although tabular and graphical risk information more effectively communicate risks than textual risk information, the cognitive mechanisms responsible for this enhancement are unclear. This study aimed to examine two possible mechanisms (i.e., cognitive workload and attention). Cognitive workload (mean pupil size and peak pupil dilation) and attention directed to the risk information (viewing time, number of eye fixations, and eye fixation durations) were both measured in a between‐subjects experimental design. The results suggest that graphical risk information facilitates comprehension of that information because it attracts and holds attention for a longer period of time than textual risk information. Graphs are thus a valuable asset to risk communication practice for two reasons: first, they tend to attract attention and, second, when attended to, they elicit information extraction with relatively little cognitive effort, and finally result in better comprehension.     

Cooking Practices in the Kitchen—Observed Versus Predicted Behavior

Cross-contamination and undercooking are major factors responsible for campylobacteriosis and as such should be incorporated in microbiological risk assessment. A previous paper by van Asselt et al. ^{( 1 )} quantified cross-contamination routes from chicken breast fillet via hand, cutting board, and knife ending up in a prepared chicken-curry salad in the domestic kitchen. The aim of the current article was to validate the obtained transfer rates with consumer data obtained by video observations and microbial analyses of a home prepared chicken-curry salad. Results showed a wide range of microbial contamination levels in the final salad, caused by various cross-contamination practices and heating times varying from 2'44" to 41'30". Model predictions indicated that cooking times should be at least 8 minutes and cutting boards need to be changed after cutting raw chicken in order to obtain safe bacterial levels in the final salad. The model predicted around 75% of the variance in cross-contamination behavior. Accuracy of the model can further be improved by including other cross-contamination routes besides hands, cutting boards, and knives. The model proved to be fail-safe, which implies it can be used as a worst-case estimate to assess the importance of cross-contamination in the home.