Is econometrics useful for private policy making? A case study of replacement policy at an auto rental company

The goal of this paper is to illustrate the potential usefulness of econometrics as a tool to assist private policy makers. We provide a case study and detailed econometric analysis of the automobile replacement policy adopted by a large car rental company. Unlike public policy making–where the benefits from using econometric models and “science-based” approaches to policy making are hard to quantify because the outcomes of interest are typically subjective quantities such as “social welfare”–in the case of firms there is an objective, easily quantifiable criterion for judging whether policy A is better than policy B: profits. We introduce and estimate an econometric model of the rental histories of individual cars in the company’s fleet. Via stochastic simulations, we show that the model provides a good approximation to the company’s actual operations. In particular, the econometric model is able to reproduce the extraordinarily high rates of return that the company obtains on its rental cars, with average internal rates of return between purchase and sale of approximately 50%. However, the econometric model can simulate outcomes under a range of counterfactual vehicle replacement policies. We use the econometric model to simulate the profitability of an alternative replacement policy under pessimistic assumptions about the rate maintenance costs would increase and rental rates would have to be decreased if the company were to keep its rental cars longer than it does under the status quo. Depending on the vehicle type, we find that the company’s expected discounted profits would be between 6% to over 140% higher under the suggested alternative operating strategy where vehicles are kept longer and rental rates of older vehicles are discounted to induce customers to rent them. The company found this analysis to be sufficiently convincing that it undertook an experiment to verify the predictions of the econometric model.     

地方产业集群升级的两维性分析

发展中国家大多数地方产业集群处于低端市场竞争的低端路线,迫切需要产业升级。通过论述全球价值链背景下的集群创新与升级的互动关系,提出了产业集群升级的两维性机理及其实现要素：既要提升集群区位的“内生性要素”对创新活动的影响,包括生产要素升级、区域品牌升级、社会资本升级、区域创新系统升级;也需要借助全球网络联系对获取知识等资源的杠杆利用,提升市场、技术能力。这样,建立在持续性创新的基础上,才能保证嵌入全球价值链的地方产业集群创造、保持和捕捉更多的价值。     

政府监督下建设主体群体学习行为特征分析

建设工程质量政府监督的目的在于有效地保证公众和国家质量利益。在政府质量监督机构监督下,某个建设主体的质量行为是随机的,但随着时间的推移,某类建设主体采取某种质量行为的概率是固定的,建设主体群体学习行为符合马尔可夫特征,满足生灭过程。因此,政府监督机构应该根据各个建设主体的群体质量行为特征制定相应的激励与约束机制,以求在一定的监督力度下,实现监督效益最大化,保证质量总体水平不断提高。     

中国国内价值链是怎样形成的？

本文基于区域间投入产出模型进行区域增加值分解,通过构建国内价值链广度、国内价值链深度、国内价值链匹配度等指标,实证研究发现20世纪90年代中期以来中国重化工部门的国内价值链广度高于轻工部门,但同时呈现出下降的趋势。各部门的国内价值链深度逐年提升,其中,内资主导及市场导向型外资推动的国内价值链深度相对更高,而成本导向型外资为主的国内价值链深度较低。各部门的国内价值链匹配度渐趋合理,但仍存在很大程度的资源配置扭曲。     

Price relationships between qualitatively differentiated agricultural products: organic and conventional wheat in Germany

Organic agriculture, which produces commodities that can be qualitatively differentiated from conventional food products, has grown into an important market in many countries. The dynamics of commodity prices in both sectors are partly interdependent, but are also shaped by independent determinants and have rarely been studied. We analyze organic food markets and their interdependencies with conventional markets in the context of wheat markets in Germany, which have been subject to a number of fundamental changes during the last two decades. Based on institutional market characteristics, we suggest a flexible Markov‐switching asymmetric time series model. We find a pronounced temporal sequence of market phases that differ in their asymmetric dynamics and the extent to which the organic price is influenced by the conventional price. Organic wheat prices tend to be increasingly connected to prices of conventional wheat.     

供应链管理中的牛鞭效应研究

"牛鞭效应"是供应链管理中一种普遍存在的现象,随着经济的发展,竞争的加剧,如何消除"牛鞭效应"产生的危害,已经成为人们关注的一个问题。文中通过对"牛鞭效应"的定量分析,提出了缓解"牛鞭效应"的若干建议。     

Estimation methods for stochastic volatility models: a survey

Abstract.  Although stochastic volatility (SV) models have an intuitive appeal, their empirical application has been limited mainly due to difficulties involved in their estimation. The main problem is that the likelihood function is hard to evaluate. However, recently, several new estimation methods have been introduced and the literature on SV models has grown substantially. In this article, we review this literature. We describe the main estimators of the parameters and the underlying volatilities focusing on their advantages and limitations both from the theoretical and empirical point of view. We complete the survey with an application of the most important procedures to the S&P 500 stock price index.     

VMI对医药供应链中零售商和批发商的利益影响研究

随着政府对医药卫生行业监管的加强,医药的流通环节已成为医药行业变革的重点之一。通过对行业产品及供应链特性的分析,本文提出医药行业实施供应商库存管理(VMI)是迎接变革的一个有效途径,然后定性定量地研究VMI如何增加医药零售商、批发商和整个供应链的利润。本文也给出VMI协调医药供应链的条件,以及批发商如何通过自身的管理提升来实现自我激励和促成同零售商的共赢。     

会展供应链结构优化模型构建与系统优化

考虑到中国会展产业的迅速发展和供应链管理特点,本文基于制造供应链和服务供应链管理理论,结合会展产业自身特征,在对会展供应链进行定义的基础上,构建会展供应链结构优化模型,并针对该优化模型提出具体的优化内容和措施。研究表明,会展供应链融合了制造供应链和服务供应链的特性和内容,其绩效提高的关键在于优化自身组织结构、实现参与主体的信息共享并约束参与主体的行为。     

供应链环境下的企业物流成本管理初探

当今社会,企业面临的竞争环境越来越激烈。改善物流管理、有效降低物流成本是企业应对挑战的一条可行之路。文中从供应链的角度,对物流成本管理进行了探讨,为企业合理优化物流流程和物流成本管理提供了一种有益的参考。