Testing Hypotheses in Nonparametric Models of Production

Data envelopment analysis (DEA) and free disposal hull (FDH) estimators are widely used to estimate efficiency of production. Practitioners use DEA estimators far more frequently than FDH estimators, implicitly assuming that production sets are convex. Moreover, use of the constant returns to scale (CRS) version of the DEA estimator requires an assumption of CRS. Although bootstrap methods have been developed for making inference about the efficiencies of individual units, until now no methods exist for making consistent inference about differences in mean efficiency across groups of producers or for testing hypotheses about model structure such as returns to scale or convexity of the production set. We use central limit theorem results from our previous work to develop additional theoretical results permitting consistent tests of model structure and provide Monte Carlo evidence on the performance of the tests in terms of size and power. In addition, the variable returns to scale version of the DEA estimator is proved to attain the faster convergence rate of the CRS-DEA estimator under CRS. Using a sample of U.S. commercial banks, we test and reject convexity of the production set, calling into question results from numerous banking studies that have imposed convexity assumptions. Supplementary materials for this article are available online.     

阅读毛泽东文本：认识论问题

毛泽东的认识论并非严格意义上的经验主义,而是经验主义和理性主义的混合物。研究毛泽东的思想需要理论干预,应将其文本看作理论推演的实体,并关注文本中现有的理论主张、合乎逻辑的假设和建构方式及其相互间的关系以及这些关系的一致性和连贯性程度。     

Ordering competition: the interactional accomplishment of the sale of art and antiques at auction

Auctions provide an institutional solution to a social problem; they enable the legitimate pricing and exchange of goods where those goods are of uncertain value. In turn, auctions raise a number of social and organizational issues that are resolved within the interaction that arise in sales by auction. In this paper, we examine sales of fine art, antiques and objets d'art and explore the ways in which auctioneers mediate competition between buyers and establish a value for goods. In particular, we explore how bids are elicited, co-ordinated and revealed so as to rapidly escalate the price of goods in a transparent manner that enables the legitimate valuation and exchange of goods. In directing attention towards the significance of the social interaction, including talk, visual and material conduct, the paper contributes to the growing corpus of ethnographic studies of markets. It suggests that to understand the operation of markets and their outcomes, and to unpack issues of agency, trust and practice, we need to place the 'interaction order' at the heart of analytic agenda.     

Urge to Gamble in Problem Gamblers Exposed to a Casino Environment

Cue-reactivity has received increased attention in addiction research, though not for gambling in particular. We examined cue reactivity in 18 problem gamblers by accompanying them to a gaming casino and measuring their subjective urge to gamble over a 1-h period. Half of the sample was additionally exposed to a gambling-specific negative mood induction (NMI) manipulation via guided imagery. Overall, about two-thirds of the sample reported moderate to high-gambling urges during the casino exposure. Additionally, the NMI reduced cue-reactivity. Finally, gambling urges in both groups decreased over the course of the exposure sessions. These findings suggest that a majority of problem gamblers experience the urge to gamble when exposed to gambling cues and that the intensity of these urges decrease with time, especially in the presence of a gambling-relevant NMI. Cue exposure should be studied further as a potential tool in the treatment of problem gambling.     

Reassessing racial and socioeconomic disparities in environmental justice research

The number of studies examining racial and socioeconomic disparities in the geographic distribution of environmental hazards and locally unwanted land uses has grown considerably over the past decade. Most studies have found statistically significant racial and socioeconomic disparities associated with hazardous sites. However there is considerable variation in the magnitude of racial and socioeconomic disparities found; indeed, some studies have found none. Uncertainties also exist about the underlying causes of the disparities. Many of these uncertainties can be attributed to the failure of the most widely used method for assessing environmental disparities to adequately account for proximity between the hazard under investigation and nearby residential populations. In this article, we identify the reasons for and consequences of this failure and demonstrate ways of overcoming these shortcomings by using alternate, distance-based methods. Through the application of such methods, we show how assessments about the magnitude and causes of racial and socioeconomic disparities in the distribution of hazardous sites are changed. In addition to research on environmental inequality, we discuss how distance-based methods can be usefully applied to other areas of demographic research that explore the effects of neighborhood context on a range of social outcomes.     

Assembly Line Balancing Using Genetic Algorithms with Heuristic-Generated Initial Populations and Multiple Evaluation Criteria*

We use genetic algorithms (GA) to solve the assembly line balancing (ALB) problem. Inparticular, we show how this technique can be used to generate feasible line balances, improve upon solutions obtained by other heuristics reported in the literature, and utilizeany one or more evaluation criteria that can be expressed in functional form. The procedure is demonstrated with two examples: (1) intimating the improvement of heuristic-generated ALB solutions by including them in the GA initial population, and (2) the possibility of balancing assembly lines with multiple criteria and side constraints. These examples suggest that GA can be a powerful tool in ALB. To investigate the utility of GA on single-criterion problems, an experiment is conducted that compares both the GA approach and conventional heuristics. Results indicate that the GA solutions are significantly improved over the heuristic solutions under the conditions studied. It is also found that the presence of heuristic-generated conventional solutions in the GA initial population leads to statistically preferred results.     

A Learning Curve Analysis of Expert System Use*

In this article, we study how an expert system affects novice problem solving in a financial risk analysis domain. We demonstrate that novice performance is improved after exposure to an expert system. Further, we show that novice performance continues to improve when the system is withdrawn. By comparing learning curves for people with exposure to those without, we can assess how much the system has benefitted its users. We demonstrate a quantitative methodology to measure the increment of learning due to the use of an information technology. We also explore the issue of how expertise is transferred from the system to the user.