When Does a Platform Create Value by Limiting Choice?

We present a theory for why it might be rational for a platform to limit the number of applications available on it. Our model is based on the observation that even if users prefer application variety, applications often also exhibit direct network effects. When there are direct network effects, users prefer to consume the same applications to benefit from consumption complementarities. We show that the combination of preference for variety and consumption complementarities gives rise to (i) a commons problem (to better satisfy their individual preference for variety, users have an incentive to consume more applications than the number that maximizes joint utility); (ii) an equilibrium selection problem (consumption complementarities often lead to multiple equilibria, which result in different utility levels for the users); and (iii) a coordination problem (lacking perfect foresight, it is unlikely that users will end up buying the same set of applications). The analysis shows that the platform can resolve these problems and create value by limiting the number of applications available. By limiting choice, the platform may create new equilibria (including the allocation that maximizes users' utility); eliminate equilibria that give lower utility to the users; and reduce the severity of the coordination problem faced by users.     

New challenges in professional cleaning: hygiene quality and monitoring of surfaces in private domestic homes

In many countries, changes in the pattern of working lives and ageing of the population increases the need for professional cleaning in private domestic homes. The objective of this study was to obtain basic knowledge concerning professional home cleaning. The study consisted of two parts. First, cleanability of surfaces contaminated with microbiological and organic soils was examined in the laboratory using cleaning cloths, detergents and rapid detection methods with potential for use in conjunction with professional cleaning in private homes. Second, hygienic conditions in three households were screened using the same rapid detection methods as in the laboratory experiments. According to the laboratory study, the cleaning efficiency of the non‐woven cloth was clearly poorer than that of the cleaning cloths containing microfibers. There were differences between the efficacy of the cleaning agents in removal of protein and microbiological soils. Despite the differences between surface topography observed with scanning electron microscopy, differences between the cleanability of the three examined surface materials (steel and two plastic surfaces) were small. In hygiene monitoring, the highest levels of total aerobic bacterial counts were detected in the plughole of the sink, on the eating table in kitchens and along the edge of the toilet washbowl and the cover of toilet seats. Low amounts of Enterobacteriaceae indicating faecal contamination were detected in the toilet and bathroom after cleaning. Moulds were not detected in any of the three households, and the amounts of yeasts were low. Detection methods, microbiological dipslides and the protein test, were well suited to the laboratory study. Furthermore, they complemented each other in the hygiene monitoring. The information obtained will be used for development of better practices in professional home cleaning. Good quality management in professional home cleaning and the cleanliness of surfaces in homes are important factors affecting comfort and safety.     

家庭最优化论

一、引言这篇文章的主旨是为了阐述发展家庭最优化理论在如何帮助消费者更加有效地管理家庭资源这个问题上的重要性。最优化是指获得最佳结果。对企业来说,最优化是达到利润的最大化;对家庭来讲,最优化则是达到最大满意度。为了使分析研究切实可行,我们通常会选择一个具体的目标。譬如,对于一个企业来说,存货成本的最小化就是一个合理的最优化目标。从数学角度来看,最优化可以被看成是“到达山顶”。Intriligator(1971)已经描述了几个最优化问题的决定性因素:时间(静态和动态)、约束方式(无约束、等式约束、不等式约束)和决策者人数(一个或…     

Does Cost-Share Replicate Water Quality Trading Projects? Implications for a Possible Partnership

Water Quality Trading (WQT) and federal conservation programs such as the Environmental Quality Incentives Program (EQIP) employ incentive payments to encourage agricultural best management practices (BMPs). In many cases, WQT and EQIP are encouraging the same types of farmers to implement the same types of BMPs using similar incentive payments. A number of analysts have recommended that WQT partner with EQIP to recruit farmers, yet the literature lacks an analysis of whether EQIP could adequately substitute for WQT's project selection process. In this article, we systematically compare the project ranking procedures used by WQT and EQIP and suggest which partnership structures might be most appropriate.