Quantitative Risk Assessment: Developing a Bayesian Approach to Dichotomous Dose–Response Uncertainty

Model averaging for dichotomous dose–response estimation is preferred to estimate the benchmark dose (BMD) from a single model, but challenges remain regarding implementing these methods for general analyses before model averaging is feasible to use in many risk assessment applications, and there is little work on Bayesian methods that include informative prior information for both the models and the parameters of the constituent models. This article introduces a novel approach that addresses many of the challenges seen while providing a fully Bayesian framework. Furthermore, in contrast to methods that use Monte Carlo Markov Chain, we approximate the posterior density using maximum a posteriori estimation. The approximation allows for an accurate and reproducible estimate while maintaining the speed of maximum likelihood, which is crucial in many applications such as processing massive high throughput data sets. We assess this method by applying it to empirical laboratory dose–response data and measuring the coverage of confidence limits for the BMD. We compare the coverage of this method to that of other approaches using the same set of models. Through the simulation study, the method is shown to be markedly superior to the traditional approach of selecting a single preferred model (e.g., from the U.S. EPA BMD software) for the analysis of dichotomous data and is comparable or superior to the other approaches.     

Plots of Conditional Wait-Time Intervals Provide Better Information to Queueing System Arrivals

The management of queues is a very important aspect of service operations management. One way to enhance the queueing experience is to provide customers with the most informative and certain estimate of anticipated wait time. This paper develops such a measure—referred to as the conditional wait-time interval (CWTI)—for queueing systems with exponentially distributed service times. It is especially applicable at the operational level of an organization since it utilizes the most current information on the status of the system (number of customers in the queue at arrival). CWTI is also based on two risk factors that consider the chance a customer's actual wait time is outside of the estimated range. This paper also provides a graphical means to display multiple CWTIs.     

以能力为本位的课程创新体系的实践

灵活、创新、技能传授、再培训、就业导向是高职教育的特点,合理的课程创新体系是实现高职特点的保证。我国高职教育课程模式在培养人才职业综合素质和职业道德方面明显存在缺陷,为此我们结合中澳职业教育与培训国家项目的实践,打破传统学科体系框架,依照行业的能力标准,对课程设置、教学设计和授课方式等进行全方位的改革,得到学生、行业的认同,值得推广。     

BARGAINING BEHAVIOR IN A BUSINESS SIMULATION GAME *

Three studies of labor-management negotiations were conducted within the context of a business simulation game. Face-to-face bargaining lasted approximately two hours and resulted in settlements that were incorporated into the simulation game parameters. A total of 56 simulated companies, each comprised of five MBA students, were studied. Results from the first study showed that extending low initial offers, extracting large first concessions, and making a high number of concessions were management bargaining tactics associated with obtaining a low wage rate. These findings were supported by study two. The third study found that an intrateam power mode of orientation was positively correlated with bargaining success and was negatively correlated with overall game success. The results support the use of a simulation game for teaching and research in bargaining.     

Note on Second-Order Polynomial Regression Models

Polynomial regression models have applications in the social sciences and in business research. Unfortunately, such models have a high degree of multicollinearity that creates problems with the statistical assessment of the model. In fact, the collinearity may be so severe that it could lead to an incorrect conclusion that some of the terms in the model are not statistically significant and should therefore be omitted from the model. This note provides a simple transformation to achieve orthogonality in polynomial models between the linear and quadratic terms, thereby eliminating the collinearity problem. It also shows that the same procedure does not achieve orthogonality for higher-order terms. An example data set is analyzed to show the benefits of such a procedure.     

FINANCIAL FRAGILITY,LIQUIDITY, AND ASSET PRICES

We define a financial system to be fragile if small shocks have disproportionately large effects. In a model of financial intermediation, we show that small shocks to the demand for liquidity cause either high asset‐price volatility or bank defaults or both. Furthermore, as the liquidity shocks become vanishingly small, the asset‐price volatility is bounded away from zero. In the limit economy, with no shocks, there are many equilibria. However, if banks face idiosyncratic liquidity shocks, then the only equilibria that are robust to the introduction of small aggregate risk involve stochastic consumption as well as volatile asset, prices. (JEL: D5, D8, G2)