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非因果向量自回归模型AI 解读

In this paper, we propose a new noncausal vector autoregressive (VAR) model for non-Gaussian time series. The assumption of non-Gaussianity is needed for reasons of identifiability. Assuming that the error distribution belongs to a fairly general class of elliptical distributions, we develop an asymptotic theory of maximum likelihood estimation and statistical inference. We argue that allowing for noncausality is of particular importance in economic applications that…

失业救济期限、失业持续时间与工作匹配质量：断点回归方法AI 解读

SUMMARY We use a sharp discontinuity in the maximum duration of benefit entitlement to identify the effect of extended benefit duration on unemployment duration and post‐unemployment outcomes (employment stability and re‐employment wages). We address dynamic selection, which may arise even under an initially random assignment to treatment, estimating a bivariate discrete‐time hazard model jointly with a wage equation and correlated unobservables. Owing to the…

青少年对附带就学条件的现金转移的反应：准实验研究AI 解读

SUMMARY We estimate the effect of cash transfers given to youth conditional on high school attendance on the labor supply decisions and academic performance of youth. We exploit differences in the size of the total transfer received based on timing of birth to identify the causal effects of interest. Specifically, individuals born late in a quarter receive a larger total transfer than comparable individuals born early in the following quarter. We find that the transfer…

因果推断中忠实性假设的几何结构AI 解读

Many algorithms for inferring causality rely heavily on the faithfulness assumption. The main justification for imposing this assumption is that the set of unfaithful distributions has Lebesgue measure zero, since it can be seen as a collection of hypersurfaces in a hypercube. However, due to sampling error the faithfulness condition alone is not sufficient for statistical estimation, and strong-faithfulness has been proposed and assumed to achieve uniform or…

利用数据组合评估处理分配规则AI 解读

In real life, individuals are often assigned to binary treatments according to existing treatment protocols. Such protocols, when designed with “taste-based” motives, would be productively inefficient in that the expected returns to treatment for a marginal treatment recipient would vary across covariates and be larger for discriminated groups. This cannot be directly tested if assignment is based on more covariates than the researcher observes, because then the marginal…

美联储紧急流动性工具有多有效？资产支持商业票据流动性工具的证据AI 解读

ABSTRACT The events following Lehman's failure in 2008 and the current turmoil emanating from Europe highlight the structural vulnerabilities of short‐term credit markets and the role of central banks as back‐stop liquidity providers. The Federal Reserve's response to financial disruptions in the United States importantly included the creation of liquidity facilities. Using a differences‐in‐differences approach, we evaluate one of the most unusual of these interventions—the…

函数系数工具变量模型的局部线性 GMM 估计及教育回报应用AI 解读

We consider the local linear generalized method of moment (GMM) estimation of functional coefficient models with a mix of discrete and continuous data and in the presence of endogenous regressors. We establish the asymptotic normality of the estimator and derive the optimal instrumental variable that minimizes the asymptotic variance-covariance matrix among the class of all local linear GMM estimators. Data-dependent bandwidth sequences are also allowed for. We propose a…

非差异性误测的有序及粗化混杂变量的偏差衰减结果AI 解读

Suppose we are interested in the effect of a binary treatment on an outcome where that relationship is confounded by an ordinal confounder. We assume that the true confounder is not observed, rather we observe a nondifferentially mismeasured version of it. We show that under certain monotonicity assumptions about its effect on the treatment and on the outcome, an effect measure controlling for the mismeasured confounder will fall between its corresponding crude and the true…

随机实验中通过后分层调整处理效应估计AI 解读

Summary Experimenters often use post-stratification to adjust estimates. Post-stratification is akin to blocking, except that the number of treated units in each stratum is a random variable because stratification occurs after treatment assignment. We analyse both post-stratification and blocking under the Neyman–Rubin model and compare the efficiency of these designs. We derive the variances for a post-stratified estimator and a simple difference-in-means estimator under…

实验干预下稀疏因果高斯网络的学习：正则化与坐标下降AI 解读

Causal networks are graphically represented by directed acyclic graphs (DAGs). Learning causal networks from data is a challenging problem due to the size of the space of DAGs, the acyclicity constraint placed on the graphical structures, and the presence of equivalence classes. In this article, we develop an L 1-penalized likelihood approach to estimate the structure of causal Gaussian networks. A blockwise coordinate descent algorithm, which takes advantage of the…

观察性研究中的效应修饰与设计敏感性AI 解读

In an observational study of treatment effects, subjects are not randomly assigned to treatment or control, so differing outcomes in treated and control groups may reflect a bias from nonrandom assignment rather than a treatment effect. After adjusting for measured pretreatment covariates, perhaps by matching, a sensitivity analysis determines the magnitude of bias from an unmeasured covariate that would need to be present to alter the conclusions of the naive analysis that…

整群随机试验数据的嵌套Dirichlet过程分析：老年照护评估应用AI 解读

In cluster randomized trials, patients seen by the same physician are randomized to the same treatment arm as a group. Besides the natural clustering of patients due to cluster/group randomization, interactions between an individual patient and the attending physician within the group could just as well influence patient care outcomes. Despite the intuitive relevance of these interactions to treatment assessment, few studies have thus far examined their influences. Whether…

南非的 HIV 感染状况与劳动力市场参与AI 解读

We use econometric methods based on the propensity score to estimate the causal effect of HIV status on employment outcomes in South Africa. Relying on rich data from a national survey, which included HIV testing, we control for systematic differences between HIV-positive and HIV-negative individuals. We provide the first nationally representative estimates of the impact of HIV status on employment outcomes for southern Africa. Being HIV positive is associated with an…

处理效应的持续期依赖与未观测异质性：瑞典就业培训与就业转移率AI 解读

SUMMARY The effect of a treatment on the hazard rate of a duration outcome may depend on the elapsed time since treatment. In addition, treatment effects may be heterogeneous across agents. The former gives rise to duration dependence of the treatment effect, whereas unobserved heterogeneity gives rise to spurious duration dependence of the observable hazard rate. We develop a model allowing for duration dependence and unobserved heterogeneity in the treatment effect. The…

Napster对唱片销量的影响：构成变化下的双重差分估计AI 解读

SUMMARY This paper measures the effect of Napster on record sales. I treat the introduction of Napster as a technological event that only Internet users experienced, and use a difference‐in‐differences (DD) approach. Because of potential compositional changes in Internet users, I examine identifying assumptions for the DD estimator under compositional changes and develop a test for identifying restrictions. To address potential bias due to compositional changes, I extend DD…

通过导数约束建模内生解释变量与异质性结构方程AI 解读

In this paper, I present a general modeling framework for nonparametric models with endogenous regressors and heterogeneity. I show that many existing models in the literature can be derived from a structural equation with unobserved heterogeneity by imposing constancy assumptions on the first and second derivatives. I consider a less restrictive model that imposes constancy assumptions on the second partial derivative of the structural equation. Assuming the existence of…

混杂变量的定义AI 解读

The causal inference literature has provided a clear formal definition of confounding expressed in terms of counterfactual independence. The literature has not, however, come to any consensus on a formal definition of a confounder, as it has given priority to the concept of confounding over that of a confounder. We consider a number of candidate definitions arising from various more informal statements made in the literature. We consider the properties satisfied by each…

社会互动下处理反应的识别AI 解读

This paper studies identification of potential outcome distributions when treatment response may have social interactions. Defining a person's treatment response to be a function of the entire vector of treatments received by the population, I study identification when non‐parametric shape restrictions and distributional assumptions are placed on response functions. An early key result is that the traditional assumption of individualistic treatment response is a polar case…

延迟响应的组序贯检验（附讨论）AI 解读

Summary Group sequential methods are used routinely to monitor clinical trials and to provide early stopping when there is evidence of a treatment effect, a lack of an effect or concerns about patient safety. In many studies, the response of clinical interest is measured some time after the start of treatment and there are subjects at each interim analysis who have been treated but are yet to respond. We formulate a new form of group sequential test which gives a proper…

针对缺失值与观察性研究进行处理前变量调整的Mann–Whitney检验AI 解读

Summary The conventional Wilcoxon or Mann–Whitney test can be invalid for comparing treatment effects in the presence of missing values or in observational studies. This is because the missingness of the outcomes or the participation in the treatments may depend on certain pretreatment variables. We propose an approach to adjust the Mann–Whitney test by correcting the potential bias via consistently estimating the conditional distributions of the outcomes given the…

快速就业还是长期人力资本积累？不同培训方案的动态效应AI 解读

This article investigates how precisely short-term, job search-oriented training programs as opposed to long-term, human capital intensive training programs work. We evaluate and compare their effects on time until job entry, stability of employment, and earnings. Further, we examine the heterogeneity of treatment effects according to the timing of training during unemployment as well as across different subgroups of participants. We find that participating in short-term…

援助与增长争论中的联立性问题AI 解读

SUMMARY This paper shows that foreign aid has a significant positive average effect on real per capita gross domestic product (GDP) growth if, and only if, the quantitatively large negative reverse causal effect of per capita GDP growth on foreign aid is adjusted for in the growth regression. Instrumental variables estimates show that a 1 percentage point increase in GDP per capita growth decreased foreign aid by over 4%. Adjusting for this quantitatively large, negative…

识别技术溢出与产品市场竞争AI 解读

The impact of R&D on growth through spillovers has been a major topic of economic research over the last thirty years. A central problem in the literature is that firm performance is affected by two countervailing “spillovers” : a positive effect from technology (knowledge) spillovers and a negative business stealing effects from product market rivals. We develop a general framework incorporating these two types of spillovers and implement this model using measures of a…

非可分面板模型中的平均效应与分位数效应AI 解读

Nonseparable panel models are important in a variety of economic settings, including discrete choice. This paper gives identification and estimation results for nonseparable models under time-homogeneity conditions that are like “time is randomly assigned” or “time is an instrument.” Partial-identification results for average and quantile effects are given for discrete regressors, under static or dynamic conditions, in fully nonparametric and in semiparametric models, with…