Finding the best treatment under heavy censoring and hidden bias

Summary.  We analyse male survival duration after hospitalization following an acute myocardial infarction with a large ( N =11024) Finnish data set to find the best performing hospital district (and to disseminate its treatment protocol). This is a multiple-treatment problem with 21 treatments (i.e. 21 hospital districts). The task of choosing the best treatment is difficult owing to heavy right censoring (73%), which makes the usual location measures (the mean and median) unidentified; instead, only lower quantiles are identified. There is also a sample selection issue that only those who made it to a hospital alive are observed (54%); this becomes a problem if we wish to know their potential survival duration after hospitalization, if they had survived to a hospital contrary to the fact. The data set is limited in its covariates—only age is available—but includes the distance to the hospital, which plays an interesting role. Given that only age and distance are observed, it is likely that there are unobserved confounders. To account for them, a sensitivity analysis is conducted following pair matching. All estimators employed point to a clear winner and the sensitivity analysis indicates that the finding is fairly robust.     

新经济时代企业采购战略研究

21世纪是新经济时代,新经济与传统经济不同,以经济全球化、竞争链条化和技术网络化为特征。新经济导致企业的竞争环境发生了变化,由过去企业间的竞争转变为供应链间的竞争,企业生存环境越加复杂和多变。为此,企业已不能单纯依靠降低内部运营成本来获取更大的利润。企业如何与供应商合作,如何选择正确的采购战略尤为重要。新经济时代的采购战略主要有：供应商整合战略、供应商的全面质量管理战略、全球采购战略、供应商的长期合作关系战略、供应商提早参与战略、供应商发展战略、在线逆向拍卖战略、集中采购战略、联合采购战略和电子采购战略。企业应根据自身的发展目标和资源以及本企业总的发展战略合理选择适宜的采购战略,这样才能有效地提高自身的竞争力,实现可持续发展。     

Large Matching Markets as Two‐Sided Demand Systems

This paper studies two‐sided matching markets with non‐transferable utility when the number of market participants grows large. We consider a model in which each agent has a random preference ordering over individual potential matching partners, and agents' types are only partially observed by the econometrician. We show that in a large market, the inclusive value is a sufficient statistic for an agent's endogenous choice set with respect to the probability of being matched to a spouse of a given observable type. Furthermore, while the number of pairwise stable matchings for a typical realization of random utilities grows at a fast rate as the number of market participants increases, the inclusive values resulting from any stable matching converge to a unique deterministic limit. We can therefore characterize the limiting distribution of the matching market as the unique solution to a fixed‐point condition on the inclusive values. Finally we analyze identification and estimation of payoff parameters from the asymptotic distribution of observable characteristics at the level of pairs resulting from a stable matching.     

企业家社会资本与企业成长阶段的匹配性研究

企业家社会资本是企业获得持续成长所需的不可或缺的资源。企业家社会资本可以从微观、中观和宏观进行层次界定,企业家社会资本与企业成长各阶段具有非常高的匹配关系,企业成长的不同阶段通过构建相应类型的社会关系网络,获取相应类型的社会关系网络关键资源,保证了企业的持续经营和健康发展。     

A matching prior for the product of normal means based on the modified profile likelihood

In this paper, we develop a matching prior for the product of means in several normal distributions with unrestricted means and unknown variances. For this problem, properly assigning priors for the product of normal means has been issued because of the presence of nuisance parameters. Matching priors, which are priors matching the posterior probabilities of certain regions with their frequentist coverage probabilities, are commonly used but difficult to derive in this problem. We developed the first order probability matching priors for this problem; however, the developed matching priors are unproper. Thus, we apply an alternative method and derive a matching prior based on a modification of the profile likelihood. Simulation studies show that the derived matching prior performs better than the uniform prior and Jeffreys’ prior in meeting the target coverage probabilities, and meets well the target coverage probabilities even for the small sample sizes. In addition, to evaluate the validity of the proposed matching prior, Bayesian credible interval for the product of normal means using the matching prior is compared to Bayesian credible intervals using the uniform prior and Jeffrey’s prior, and the confidence interval using the method of Yfantis and Flatman.     

Do active labor market policies for welfare recipients in Germany raise their regional outflow into work?

While many studies estimate the effects of active labor market programs (ALMPs) on the participants’ labor market outcomes, far fewer studies are concerned with the effects of these policies on the regional job-matching process. We analyze which ALMPs are particularly effective at the regional level, as well as the role local labor market conditions play for their effectiveness. We find positive effects for a number of ALMPs, but for some of these the effects differ considerably between regions with high and low unemployment. This has important policy implications.     

浅谈《墨经》中的“侔”式

一直以来“侔”式都是《墨经》研究的重点,是中国古代特有的一种从语义角度进行推类的形式,包括是而然、是而不然、不是而然、一周而一不周、一是而一非五种形式的推类。在实际应用中,必须结合规则,遵循习惯,才能尽量避免谬误的产生。     

Justifying an Invalid Derivation of the Probability of a Union of Events

An appealing, but invalid, derivation of the probability that at least one of n events occurs is justified, using a particular definition of subtraction of events. The probabilities that exactly m and at least m of the n events occur are derived similarly.     

A Practical Procedure to Find Matching Priors for Frequentist Inference

We present a practical way to find matching priors via the use of saddlepoint approximations and obtain p-values of tests of an interest parameter in the presence of nuisance parameters. The advantages of our procedure are the flexibility in choosing different initial conditions so that one may adjust the performance of a test, and the less intensive computational efforts compared to a Markov Chain Monto Carlo method.     

Noninformative priors for the generalized half-normal distribution

In this paper, we develop noninformative priors for the generalized half-normal distribution when scale and shape parameters are of interest, respectively. Especially, we develop the first and second order matching priors for both parameters. For the shape parameter, we reveal that the second order matching prior is a highest posterior density (HPD) matching prior and a cumulative distribution function (CDF) matching prior. In addition, it matches the alternative coverage probabilities up to the second order. For the scale parameter, we reveal that the second order matching prior is neither a HPD matching prior nor a CDF matching prior. Also, it does not match the alternative coverage probabilities up to the second order. For both parameters, we present that the one-at-a-time reference prior is a second order matching prior. However, Jeffreys’ prior is neither a first nor a second order matching prior. Methods are illustrated with both a simulation study and a real data set.