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用倾向得分匹配估计反贫困项目的受益分布AI 解读

problem of estimating the distribution of net income gains from an Argentinean workfare program. PSM has a number of attractive features in this context, including the need to allow for heterogeneous impacts, while optimally weighting observed characteristics when forming a comparison group. The average direct gain to the participant is found to be about half the gross wage. Over half of the beneficiaries are in the poorest decile nationally, and 80% are in the poorest…

是否存在 Riverside 奇迹？利用分组数据评估项目的层级框架AI 解读

sites. Two frequently used methods are pooling the data or using fixed effects (an extreme version of which estimates separate models for each site). The former approach ignores site effects. The latter incorporates site effects but lacks a framework for predicting the impact of subsequent implementations of the program (e.g., would a new implementation resemble Riverside?). I present a hierarchical model that lies between these two extremes. Using data from the Greater…

具有潜在治疗生效滞后时间的加性风险模型AI 解读

In many clinical trials for evaluating treatment efficacy, it is believed that there may exist latent treatment effectiveness lag times after which medical treatment procedure or chemical compound would be in full effect. In this paper, semiparametric regression models are proposed and studied for estimating the treatment effect accounting for such latent lag times. The new models take advantage of the invariant property of the additive hazards model in marginalising over an…

产品差异化寡头市场中的竞争结果AI 解读

This paper analyzes the effect of market concentration and product differentiation on the observed outcomes of competition among oligopolists. The empirical framework is designed to examine whether competition is less intense in markets with equal levels of concentration but more differentiation among the products offered. A two-stage estimation procedure is proposed to address the endogeneity problem inherent in comparing outcomes across different market structures. I…

链图模型及其因果解释AI 解读

Summary Chain graphs are a natural generalization of directed acyclic graphs and undirected graphs. However, the apparent simplicity of chain graphs belies the subtlety of the conditional independence hypotheses that they represent. There are many simple and apparently plausible, but ultimately fallacious, interpretations of chain graphs that are often invoked, implicitly or explicitly. These interpretations also lead to flawed methods for applying background knowledge to…

美国青年劳动力市场：频繁换工作还是保持稳定AI 解读

The need for school-to-work programs or other means of increasing early job market stability is predicated on the view that the "chaotic" nature of youth labor markets in the United States is costly because workers drift from one job to another without developing skills, behavior, or other characteristics that in turn lead to higher adult earnings. However, there is also ample evidence that workers receive positive returns to job shopping. This paper asks whether youths in…

重新分析最后通牒议价：无形状约束下的非递减曲线比较AI 解读

We employ a hierarchical Bayesian method with exchangeable prior distributions to estimate and compare similar nondecreasing response curves. A Dirichlet process distribution is assigned to each of the response curves as a first stage prior. A second stage prior is then used to model the hyperparameters. We define parameters which will be used to compare the response curves. A Markov chain Monte Carlo method is applied to compute the resulting Bayesian estimates. To…

酒精滥用与就业：重新考察AI 解读

Abstract Based on data from the 1988 Alcohol Supplement of the National Health Interview Survey, Mullahy and Sindelar ( 1996 ) (M&S) find, for both men and women, that alcohol abuse results in reduced employment and increased unemployment. The estimates from which they drew these inferences were obtained via the instrumental variables (IV) method, which was implemented in order to account for the potential endogeneity of problem drinking. Though these IV estimates…

工具变量模型中分布处理效应的自助法检验AI 解读

This article considers the problem of assessing the distributional consequences of a treatment on some outcome variable of interest when treatment intake is (possibly) nonrandomized, but there is a binaryinstrument available for the researcher. Such a scenario is common in observational studies and in randomized experiments with imperfect compliance. One possible approach to this problem is to compare the counterfactual cumulative distribution functions of the outcome with…

回顾性匹配下调整后的 Nelson–Aalen 估计AI 解读

In certain situations, randomized trials are not possible, but formal comparison of survival in two or more groups is still desirable. Although no substitute for randomization, application of the matched case-control design to survival studies may minimize the potential bias. Comparable estimates for each treatment group can be obtained by matching or stratifying according to prognostic variables, and weighting each individual to make stratum distributions the same over the…

基于疗效与死亡结果选择多疗程临床试验治疗策略AI 解读

Therapy of rapidly fatal diseases often requires multiple courses of treatment. In each course, the treatment may achieve the desired clinical goal (“response”), the patient may survive without response (“failure”), or the patient may die. When treatment fails in a given course, it is common medical practice to switch to a different treatment for the next course. Most statistical approaches to such settings simply ignore the multicourse structure. They characterize patient…

This paper considers causal inference and sample selection bias in nonexperimental settings in which (i) few units in the nonexperimental comparison group are comparable to the treatment units, and (ii) selecting a subset of comparison units similar to the treatment units is difficult because units must be compared across a high-dimensional set of pretreatment characteristics. We discuss the use of propensity score-matching methods, and implement them using data from the…

第二次世界大战与经济收敛AI 解读

Proxies that measure the effect of World War II on a country's capital stock are used as instruments for estimating standard cross-country growth regressions. The war's destruction should offer a natural experiment that allows us to consistently estimate the speed at which productivity growth converges to its long-run path. This paper presents evidence that convergence rates are approximately 4% to 6% per annum, substantially larger than conventional wisdom. © 2002 by the…

流行病学研究中的混杂因素判定标准AI 解读

Summary The paper addresses a formal definition of a confounder based on the qualitative definition that is commonly used in standard epidemiology text-books. To derive the criterion for a factor to be a confounder given by Miettinen and Cook and to clarify inconsistency between various criteria for a confounder, we introduce the concepts of an irrelevant factor, an occasional confounder and a uniformly irrelevant factor. We discuss criteria for checking these and show that…

补贴培训对受训者收入分位数影响的工具变量估计AI 解读

The effect of government programs on the distribution of participants' earnings is important for program evaluation and welfare comparisons.This paper reports es- timates of the effects of JTPA training programs on the distribution of earnings.The estimation uses a new instrumental variable (IV) method that measures program impacts on the quantiles of outcome variables.This quantile treatment effects (QTE) estimator accommodates exogenous covariates and reduces to quantile…

工具变量有效性的一种新规格检验AI 解读

We develop a new specification test for IV estimators adopting a particular second order approximation of Bekker. The new specification test compares the difference of the forward (conventional) 2SLS estimator of the coefficient of the right-hand side endogenous variable with the reverse 2SLS estimator of the same unknown parameter when the normalization is changed. Under the null hypothesis that conventional first order asymptotics provide a reliable guide to inference, the…

家庭购买时点决策的分群风险率方法AI 解读

Abstract The increasing availability of customer‐level data and the willingness of marketers to customize the timing of their offers to consumers makes the accurate segment‐level description of household purchase timing decisions a compelling issue. In this paper we employ a finite mixture accelerated failure time model to identify and characterize household segments in terms of their purchasing rates and their propensity to accelerate purchases due to marketing mix…

We extend Robins’ theory of causal inference for complex longitudinal data to the case of continuously varying as opposed to discrete covariates and treatments. In particular we establish versions of the key results of the discrete theory: the $g$-computation formula and a collection of powerful characterizations of the $g$-null hypothesis of no treatment effect. This is accomplished under natural continuity hypotheses concerning the conditional distributions of the outcome…

物种组成的统计解释AI 解读

The relative abundance of different species characterizes the structure of a biological community. We analyze an experiment addressing the relationship between omnivorous feeding linkages and community stability. Our goal is to determine whether communities with different predator compositions respond similarly to environmental disturbance. To evaluate these data, we develop a hierarchical statistical model that combines Aitchison's logistic normal distribution with a…

群组随机试验分析的最优置换检验AI 解读

Two facts complicate the comparison of interventions in group randomized trials (GRT's), a family of clinical trials in which each member of a particular group receives the same treatment assignment. First, individual outcomes within each group are often correlated. Second, the number of groups in a GRT is often not sufficient to make asymptotic approximations possible. Therefore, the tests used with methods, such as generalized estimating equations (GEE) and penalized quasi…

摘要暂缺

选择性偏差的局部敏感性近似AI 解读

Summary Observational data analysis is often based on tacit assumptions of ignorability or randomness. The paper develops a general approach to local sensitivity analysis for selectivity bias, which aims to study the sensitivity of inference to small departures from such assumptions. If M is a model assuming ignorability, we surround M by a small neighbourhood N defined in the sense of Kullback–Leibler divergence and then compare the inference for models in N with that for…