Cointegration and control: Assessing the impact of events using time series data

Control groups can provide counterfactual evidence for assessing the impact of an event or policy change on a target variable. We argue that fitting a multivariate time series model offers potential gains over a direct comparison between the target and a weighted average of controls. More importantly, it highlights the assumptions underlying methods such as difference in differences and synthetic control, suggesting ways to test these assumptions. Gains from simple and transparent time series models are analysed using examples from the literature, including the California smoking law of 1989 and German reunification. We argue that selecting controls using a time series strategy is preferable to existing data‐driven regression methods.     

加征关税如何影响美国贸易逆差及全球福利——基于美元本位下两国动态一般均衡框架的分析

本文构建了一个包含美元本位特征的两国模型,在此基础上分析了美国加征关税及引发的贸易摩擦对美国贸易逆差和全球福利的影响,并详细探讨了相关传导机制。在基准模型设定下,美国单方面加征20%关税会使得美国贸易逆差占GDP比重小幅缩小约0.40个百分点,美国长期稳态GDP下降约2.50%,其他国家GDP下降约1.10%,美国居民福利上升约0.60%,其他国家居民福利下降约1.20%。美国单方面加征关税在抑制全球贸易和生产的同时,会通过更加不公平的国际贸易恶化全球福利分配。当其他国家采取报复性措施时,其他国家自身福利并不会进一步恶化,但美国福利会大幅下滑,同时美国贸易逆差相对规模变化不大。贸易摩擦博弈的“囚徒困境”特征在一定程度上能够解释贸易战的发生。削弱美元本位地位能促进国际贸易公平性的提升,进而能减弱贸易摩擦带来的负面影响、提升全球福利水平,并能有效缩窄美国贸易逆差。     

Virtually No Effect? Different Uses of Classroom Computers and their Effect on Student Achievement

Most studies find little to no effect of classroom computers on student achievement. We suggest that this null effect may combine positive effects of computer uses without equivalently effective alternative traditional teaching practices and negative effects of uses that substitute more effective teaching practices. Our correlated random effects models exploit within‐student between‐subject variation in different computer uses in the international TIMSS test. We find positive effects of using computers to look up information and negative effects of using computers to practice skills, resulting in overall null effects. Effects are larger for students with high socioeconomic status and mostly confined to developed countries.     

施工企业引导EPC项目初步设计策划

EPC工程总承包合同模式不同于施工总承包,通常情况下业主不提供施工图纸,业主只对工程的功能性提出相应要求.承包商可以综合协调建筑的使用功能、结构安全、工期、成本等诸多因素,最大限度地发挥设计的主导作用,为业主提供优质服务的同时,增加自身的盈利水平.EPC项目不论何种模式,从成本造价控制角度讲,其设计阶段管控效果要远远大于采购与施工阶段.通过商务创效引导初步设计,从源头落实商务策划,锁定工程概算,降低EPC项目设计风险,加强设计前段管理,能有效地提升项目生产经营能力.     

LEADERSHIP IN CLIMATE CHANGE MITIGATION: CONSEQUENCES AND INCENTIVES

Initiatives in favor of unilateral action on climate change are frequently challenged by concerns over free riding. Nevertheless, we observe an increasing number of unilateral efforts at different administrative levels and in different parts of the world. Previous academic literature described various individual mechanisms where emissions abroad may increase or decrease as a reaction to unilateral emission reductions. In this paper, we collect a comprehensive set of both positive and negative reactions and analyze them in stylized models. This allows us to identify the most important characteristics that determine the potential of a leader to boost mitigation efforts abroad. We find that this potential depends on (i) a strong ability to generate knowledge through leadership, (ii) a high degree of credibility in the international community, and (iii) a similar economic structure to the most important emitters. While most effects are difficult to quantify, this comprehensive assessment suggests that leakage effects resulting from unilateral mitigation may well be outweighed by positive reactions.     

国家助学贷款中信息不对称问题及其矫正

国家助学贷款工作的实施,为帮助贫困大学生顺利完成学业发挥着重要作用。但是由于助学贷款中的信息不对称所引起的逆向选择和道德风险问题使该项工作陷入了贷还两难的窘境。因此,必须通过建立完善的信用制度,健全法律法规,设计合理的还贷激励机制,构建风险分担体系,加大高校的工作投入,使助学贷款工作能够顺利实施,发挥更大的作用。     

Motivations and barriers of foreign R&D activities in China

The continued growth of the Chinese economy accompanied with the expansion of international investment in China has led to an increase in foreign research and development (R&D) activities in the country. Aside from the rising importance of R&D internationalization, research on foreign R&D in China has been neglected in the past due to its emerging status. In this article we examine drivers and barriers for conducting R&D in China. The focus of our research is on transnational companies typically characterized by decentralized R&D activities. Our research is mainly based on qualitative interviews with senior R&D managers. The success of foreign R&D activities in China strongly depends on the realistic estimation of its advantages and the proper identification and handling of barriers.     

A Bayesian analysis of a variance decomposition for stock returns

We apply Bayesian methods to study a common vector autoregression (VAR)-based approach for decomposing the variance of excess stock returns into components reflecting news about future excess stock returns, future real interest rates, and future dividends. We develop a new prior elicitation strategy, which involves expressing beliefs about the components of the variance decomposition. Previous Bayesian work elicited priors from the difficult-to-interpret parameters of the VAR. With a commonly used data set, we find that the posterior standard deviations for the variance decomposition based on these previously used priors, including “non-informative” limiting cases, are much larger than classical standard errors based on asymptotic approximations. Therefore, the non-informative researcher remains relatively uninformed about the variance decomposition after observing the data. We show the large posterior standard deviations arise because the “non-informative” prior is implicitly very informative in a highly undesirable way. However, reasonably informative priors using our elicitation method allow for much more precise inference about components of the variance decomposition.     

永乐家电能否“永乐”京城

上海家电连锁大鄂永乐家电在经过两年筹划之后于6月18日正式登陆北京．开设了在北京的第一家店。永乐家电董事长陈晓说：“如果不拿下北京与广东的市场，永乐就谈不上是全国性的连锁。“陈晓的这番话让我们看出永乐进入北京的决心，但永乐究竟是“永乐”京城还是永乐自身，是包括像国美、苏宁这样大的家电连锁企业所共同关心的问题。