Treatment effects in sample selection models and their nonparametric estimation

In a sample-selection model with the ‘selection’ variable Q$Q$ and the ‘outcome’ variable Y^∗$Y^{\ast }$, Y^∗$Y^{\ast }$ is observed only when Q=1$Q=1$. For a treatment D$D$ affecting both Q$Q$ and Y^∗$Y^{\ast }$, three effects are of interest: ‘participation  ’ (i.e., the selection) effect of D$D$ on Q$Q$, ‘visible performance  ’ (i.e., the observed outcome) effect of D$D$ on Y≡QY^∗$Y\equiv Q{Y}^{\ast }$, and ‘invisible performance  ’ (i.e., the latent outcome) effect of D$D$ on Y^∗$Y^{\ast }$. This paper shows the conditions under which the three effects are identified, respectively, by the three corresponding mean differences of Q$Q$, Y$Y$, and Y|Q=1$Y|Q=1$ (i.e., Y^∗|Q=1$Y^{\ast }|Q=1$) across the control (D=0$D=0$) and treatment (D=1$D=1$) groups. Our nonparametric estimators for those effects adopt a two-sample framework and have several advantages over the usual matching methods. First, there is no need to select the number of matched observations. Second, the asymptotic distribution is easily obtained. Third, over-sampling the control/treatment group is allowed. Fourth, there is a built-in mechanism that takes into account the ‘non-overlapping support problem’, which the usual matching deals with by choosing a ‘caliper’. Fifth, a sensitivity analysis to gauge the presence of unobserved confounders is available. A simulation study is conducted to compare the proposed methods with matching methods, and a real data illustration is provided.     

在华外资银行的“国民待遇”

我国政府为了履行加入世贸承诺,对在华外资银行实行"国民待遇"原则,逐渐开放本国银行市场。但是在我国现阶段的国情背景下,该原则仍呈现灵活机动的状态。在如此政策背景和市场压力下,在华外资银行面临着诸多机遇与挑战。     

投资者是理性的吗?——基于ST公司交易特性和价值的分析

以1998年到2004年全部A股公司为样本,本研究系统考察了被特别处理(ST)公司的股票交易特性与估值。结果发现,当上市公司被实施ST以后,其股票交易显著偏离市场指数,呈个性化波动态势;在被实施ST期间,公司价值被显著低估。这一发现意味着投资者在投资ST股票时,总体是理性的,ST政策发挥了预期的警示作用。     

城镇居民的大学教育收益率估计:倾向指数匹配方法

本文利用全国综合社会调查数据(CGSS2003),首先使用Probit模型估计了个体上大学的概率,然后运用倾向指数匹配方法估计了2002年我国城镇居民的大学教育收益率.Probit估计结果表明家庭背景及地区对个人上大学的概率具有显著影响.匹配方法估计结果显示,大学毕业相对于高中毕业的教育收益率在79.1%以上,年均超过19.8%.传统的OLS方法估计的大学教育收益率仅为56.1%,低于匹配方法的估计结果.另外,高中组个体的潜在大学教育收益率可能高于大学组的大学教育收益率.     

The impact of license regulation on the number of recreation trips: is it worth considering?

A two-stage nonlinear least-squares model (2NLS) with an endogenous treatment effect on recreation trips describes the behavior of recreationists with and without a fishing/hunting license. The proposed 2NLS is applied to the derivation of the policy-relevant average gains in the presence of an endogeneity bias to a license fee implementation program regulated by states. Recreationists who purchased a license are likely to recreate more than are the nonlicensed holders because the regulation may reduce congestions at sites where licensee visit often. The license regulation has a greater impact on the use of natural resources after controlling observed and unobserved confounders which might be correlated with the probability of being a license holder and with the final outcome, the number of recreation trips. We confirm that the individual without a permit regards the recreation trip as less valuable than does the individual having a license permit. We also found that the likelihood of purchasing a license among young adult recreationists is not at the level the states may desire. In addition, the number of trips demanded is more responsive to the nontransportation-related implicit travel cost than to the transportation-related implicit travel cost, although travel implicit costs are price inelastic.      

区域服务贸易安排“特惠实质”的政治经济分析

区域服务贸易安排的不断蔓延标志着世界服务贸易的管理模式正在发生变化。本文基于与多边服务贸易自由化安排相对照的视角,对区域服务贸易安排提供的特惠待遇内容及实质展开政治经济分析。研究结果显示,由于区域服务贸易安排内涵着重要的"特惠侵蚀"机制:一是引入"非成员最惠国待遇条款",二是设立相对自由的服务原产地规则,实际付诸实施的区域服务贸易"特惠待遇"远不如根据协定文本测算得那么显著。从"服务"的特殊属性出发,本文指出有一系列的政治经济因素会促使区域服务贸易安排具有更强的将特惠承诺向区外扩展适用的潜在动力。区域服务贸易"特惠待遇"在本质上具有"渗漏性"这点会有助于推进多边服务贸易自由化进程。     

Partial unemployment insurance benefits and the transition rate to regular work

In Finland, unemployed workers who are looking for a full-time job but take up a part-time or very short full-time job may qualify for partial unemployment benefits. In exchange for partial benefits, these applicants must continue their search of regular full-time work. This study analyzes the implications of working on partial benefits for subsequent transitions to regular employment. The timing-of-events approach is applied to distinguish between causal and selectivity effects associated with the receipt of partial benefits. The results suggest that partial unemployment associated with short full-time jobs facilitates transitions to regular employment. Also part-time working on partial benefits may help men (but not women) in finding a regular job afterwards.     

无条件分位数处理效应方法及其应用

研究目标：政策评估在我国经济社会研究中备受关注,但所采用的方法以平均处理效应居多,分位数处理效应鲜见。与后者相关的理论和应用研究与国外尚存在较大差距,亟待跟进。研究方法：采用蒙特卡罗模拟方法比较了条件分位数处理效应（CQTE）与UQTE方法和其他UQTE方法之间的异同。研究发现：如果回归中只包含常数项和处理变量,CQTE与UQTE是等价的;如果个体在处理组和控制组中的相对位置保持不变,CQTE和UQTE都可以得到无偏估计。研究创新：通过最低工资标准提升政策对居民工资分布影响的实例说明UQTE方法在政策评价中的应用。研究价值：基于断点回归和双差分模型对新的UQTE拓展方法进行探索性展望。     

Modeling and calculating the effect of treatment at baseline from panel outcomes

We propose and examine a panel data model for isolating the effect of a treatment, taken once at baseline, from outcomes observed over subsequent time periods. In the model, the treatment intake and outcomes are assumed to be correlated, due to unobserved or unmeasured confounders. Intake is partly determined by a set of instrumental variables and the confounding on unobservables is modeled in a flexible way, varying both by time and treatment state. Covariate effects are assumed to be subject-specific and potentially correlated with other covariates. Estimation and inference is by Bayesian methods that are implemented by tuned Markov chain Monte Carlo methods. Because our analysis is based on the framework developed by Chib [2004. Analysis of treatment response data without the joint distribution of counterfactuals. Journal of Econometrics, in press], the modeling and estimation does not involve either the unknowable joint distribution of the potential outcomes or the missing counterfactuals. The problem of model choice through marginal likelihoods and Bayes factors is also considered. The methods are illustrated in simulation experiments and in an application dealing with the effect of participation in high school athletics on future labor market earnings.     

A structural analysis of the correlated random coefficient wage regression model

We estimate a dynamic programming model of schooling decisions in which the log wage regression function is set within a correlated random coefficient model. We show that estimates of the dynamic programming model can be used to obtain a number of treatment effects, including the local average treatment effect (LATE). However, unlike LATE parameters obtained in a standard IV framework, our LATE estimates are obtained without imposing separability between individual specific heterogeneity and schooling choices and are therefore not subject to a “monotonicity” restriction. We find that returns to schooling are characterized by a high degree of dispersion across individuals.