Integrated safety stock optimization for multiple sourced stockpoints facing variable demand and lead time

The safety stock placement problem of a multi-stage supply chain comprising multiple sourced stockpoints is addressed in this paper. Each stockpoint faces variability in its downstream demand and suppliers' lead time. The maximum among these suppliers' lead time is determined by employing concepts of order statistics. It is required to find the fill rate and safety stocks at each stockpoint that leads to satisfying the end customer service level at minimum safety stock placement cost. Hence, the fill rates and the safety amounts are decided from a global supply chain perspective. Two models are proposed; a decentralized safety stock placement model and a centralized consolidation model. The decentralized model finds the safety amounts at each stockpoint required to face its underlying lead time demand variability. The consolidation model finds the consolidated safety amounts that will be kept in the relevant consolidation center at each stage. A Benders decomposition technique is developed to handle the nonlinearity and binary restrictions involved in the safety stock consolidation model. Strategies proposed by the consolidation model achieve 45.2-62% reduction in safety amounts that results in a cost savings ranging between 22.2-44.2% as compared to the strategies proposed by the decentralized model.     

非线性计量经济模型的非参数估计方法研究

本文提出使用核估计的方法构造平滑转移模型(STR)的非参数模拟最大似然估计(NPSML),给出了NPSML估计量的构造方法、渐近性质以及相应的核函数和窗宽的选择准则,并利用滑动窗宽算法对估计量的构造过程进行了改进。通过Monte Carlo实验证明,该方法是可靠的,并且当误差项存在序列相关时,此种估计量是稳健的。     

Bayesian forecasting of federal funds target rate decisions

In this paper we examine which macroeconomic and financial variables have most predictive ability for the federal funds target rate decisions made by the Federal Open Market Committee (FOMC). We conduct the analysis for the 157 FOMC decisions during the period January 1990–June 2008, using dynamic ordered probit models with a Bayesian endogenous variable selection methodology and real-time data for a set of 33 candidate predictor variables. We find that indicators of economic activity and forward-looking term structure variables, as well as survey measures are most informative from a forecasting perspective. For the full sample period, in-sample probability forecasts achieve a hit rate of 90%. Based on out-of-sample forecasts for the period January 2001–June 2008, 82% of the FOMC decisions are predicted correctly.     

Analysis of treatment response data without the joint distribution of potential outcomes

In this paper we show how it is possible to develop a Bayesian framework for analyzing structural models for treatment response data without the joint distribution of the potential outcomes. That this is possible has not been noticed in the literature. We also discuss the computation of the model marginal likelihood and present recipes for finding relevant treatment effects, averaged over both parameters and covariates. As compared to an approach in which the counterfactuals are part of the prior-posterior analysis (as in the work to date), the approach we suggest is simpler in terms of the required prior inputs, computational burden and extensibility to more complex settings.     

锻炼习惯能带来更高的收入吗?

在中国城乡居民体育锻炼现状不容乐观以及居民收入水平增速不断放缓的背景下,劳动力市场中锻炼的收入效应值得深入研究。文章基于2014-2016年中国劳动力动态调查数据,使用固定效应模型、工具变量以及倾向性匹配得分方法估计个体的锻炼行为对收入水平的影响,并探讨可能的作用机制。研究结果表明,锻炼确实能够为个体带来显著的收入溢价,同时各种稳健性检验也证明了研究结论的可靠性。机制分析结果表明,锻炼行为会通过影响个体的健康水平、外貌状况以及对待工作的态度,从而影响个体的收入水平。异质性分析结果表明,年龄上,锻炼对个体收入的影响主要存在于青年阶段和中年阶段,且青年阶段的作用机制主要是外貌状况,而中年阶段的作用机制主要是健康水平;教育程度上,锻炼对收入的影响主要存在于中等教育程度的个体。本研究的结论表明,政府应当采取各种措施鼓励居民参与到体育锻炼中来,尤其是应当将中青年群体和中等教育群体吸引进来,这对于解决当前如何进一步提高居民收入水平的困境可以说是另辟蹊径。     

论实验研究法在会计研究中的应用

实验研究法是国外会计理论研究领域广泛采用的科学研究方法之一,而国内的学者使用这种研究方法的频率很低。本文将从实验研究方法概念、实验研究方法与会计研究的关系和实验研究方法在会计领域的应用范围等方面介绍这种研究方法,帮助人们进一步认识乃至熟悉和应用该研究方法,从而推动我国会计理论研究的发展。     

基于变权综合理论的物流标准化绩效评价

利用变权综合理论，提出了一种科学的综合评价方法，建立了多层次多因素的变权综合评价模型，该方法减少了传统评价方法中采用常权的不合理性，然后结合我国物流标准化的实际情况建立了物流标准化绩效评价指标体系，最后以广东某物流企业Y公司为例。通过进行专家调查评分的方法得出企业的各项评价指标的强弱情况，并进行了示例分析，结果基本符合实际情况，证明了该模型的有效性。     

效率工资的必要条件与经济效应

索洛模型和萨默斯模型存在局限性，在建立效率工资一般模型时，应当同时考虑到绝对工资水平、相对工资高低和失业率对工人劳动效率的影响。效率工资机制依赖于两个必要条件：间接计量的工资形式和竞争关系的存在。当效率工资的条件成立时，工资调整将存在粘性，均衡工资高于劳动力市场出清工资，且存在均衡失业。     

Landing on all fours? Communist elites in post-Soviet Russia

This paper analyzes the economic situation of former Communist party members in post-Soviet Russia. On the basis of the Russian Socio-Economic Transition Panel, we are able to identify members of the Communist party prior to transition so that we can assess their relative economic performance between 1993 and 1999. We find a significant wage premium associated with former membership in the Soviet Communist party during the period from 1993 to 1999. After addressing non-random selection into the Communist party using an instrumental variables approach, we demonstrate that the overall Communist wage premium can be attributed to positive unobservable characteristics of former party members. Journal of Comparative Economics 32 (4) (2004) 700–719.     

Measuring airports’ operating efficiency: a summary of the 2003 ATRS global airport benchmarking report

This paper provides a partial summary of the 2003 ATRS (Air Transport Research Society) Global Airport Benchmarking Report which uses the annual data for 2000–2001. The objective of the ATRS benchmarking report is to measure and compare the performance of several important aspects of airport management and operation: productivity and efficiency, unit costs and cost competitiveness, financial results. The report also examines the relationships between various performance measures and airport characteristics in order to better understand the observed differences in airport performance. This particular paper extracted from the benchmarking report focuses on measuring and comparing operating efficiency performance of the world’s major airports. In particular, the paper presents the results on the airports’ Variable Factor Productivities (VFP) after removing the effects of the variables beyond managerial control. In the process, it identifies the effects of various factors influencing airport’s VFP, and computes a ’residual’ VFP index as an indicator for airports’ operations efficiency.