Status Traps

In this article, we explore nonlinearities in the intergenerational mobility process using threshold regression models. We uncover evidence of threshold effects in children's outcomes based on parental education and cognitive and noncognitive skills as well as their interaction with offspring characteristics. We interpret these thresholds as organizing dynastic earning processes into “status traps.” Status traps, unlike poverty traps, are not absorbing states. Rather, they reduce the impact of favorable shocks for disadvantaged children and so inhibit upward mobility in ways not captured by linear models. Our evidence of status traps is based on three complementary datasets; that is, the PSID, the NLSY, and US administrative data at the commuting zone level, which together suggest that the threshold-like mobility behavior we observe in the data is robust for a range of outcomes and contexts.     

规模的门限效应、综合化经营与我国商业银行系统性风险

综合化经营已经成为我国商业银行应对传统业务收入比重不断降低、谋求突破性发展的重要战略。现有研究常采用非利息收入占比作为综合化经营程度的测量指标,这种做法具有明显的技术缺陷。本文将非金融企业产品多样化熵的测量指标引入到商业银行综合化经营分析,较好地解决了综合化经营程度的测量问题。基于宏观审慎与微观审慎相结合的监管理念,本文在利用成分期望损失方法测量商业银行层面系统性风险基础上,借助于动态面板门限模型重点探讨并识别了商业银行规模的门限效应,并借此区分不同的机制状态来分析综合化经营对商业银行系统性风险的影响作用。研究结果表明：综合化经营对于我国商业银行系统性风险的影响作用具有规模的门限效应,表现为规模小的商业银行开展综合化经营会降低系统性风险,规模大的商业银行开展综合化经营会增加系统性风险。     

Multiple cases deletion measures in linear measurement error models

In this paper, we define a multiple cases deletion model (MCDM) in linear measurement error models (LMEMs). Then, by using the corrected score method of Nakamura (1990), the estimation of parameters is obtained. Furthermore, Based on MCDM, we provide computationally inexpensive deletion diagnostic tools for LMEMs. An example illustrates that our method is useful for diagnosing influential subsets of observations.     

Outlier detection based on extreme value theory and applications

Whether an extreme observation is an outlier or not depends strongly on the corresponding tail behavior of the underlying distribution. We develop an automatic, data-driven method rooted in the mathematical theory of extremes to identify observations that deviate from the intermediate and central characteristics. The proposed algorithm is an extension of a method previously proposed in the literature for the specific case of heavy tailed Pareto-type distributions to all max-domains of attraction. We propose some applications such as a tail-adjusted boxplot which yields a more accurate representation of possible outliers, and the identification of outliers in a multivariate context through an analysis of associated random variables such as local outlier factors. Several examples and simulation results illustrate the finite sample behavior of the algorithm and its applications.     

论社会视阈下的大学生爱国主义教育

导致大学生爱国主义教育低效,有学校、家庭及其自身的原因,然而今天社会的消极影响尤其不可小视。文章针对社会消极影响,从净化社会风气,振奋民族精神,充分利用互联网等先进技术手段,发挥爱国主义教育基地的积极作用,以及从微观着手营造爱国主义教育宏观情境等五个方面,提供社会视阈下大学生爱国主义教育的应对之策。     

Inference and Missing Data: Asymptotic Results

In Rubin (1976) the missing at random (MAR) and missing completely at random (MCAR) conditions are discussed. It is concluded that the MAR condition allows one to ignore the missing data mechanism when doing likelihood or Bayesian inference but also that the stronger MCAR condition is in some sense the weakest generally sufficient condition allowing (conditional) frequentist inference while ignoring the missing data mechanism. In this paper it is shown that (a slightly strengthened version of) the MAR condition is sufficient to yield ordinary large sample results for estimators and test statistics and thus may be used for (asymptotic) frequentist inference.     

Estimating Benchmark Concentrations and Other Noncancer Endpoints in Epidemiology Studies

Methods for evaluating the hazards associated with noncancer responses with epidemiologic data are considered. The methods for noncancer risk assessment have largely been developed for experimental data, and are not always suitable for the more complex structure of epidemiologic data. In epidemiology, the measurement of the response and the exposure is often either continuous or dichotomous. For a continuous noncancer response modeled with multiple regression, a variety of endpoints may be examined: (1) the concentration associated with absolute or relative decrements in response; (2) a threshold concentration associated with no change in response; and (3) the concentration associated with a particular added risk of impairment. For a dichotomous noncancer response modeled with logistic regression, concentrations associated with specified added/extra risk or with a threshold responses may be estimated. No-observed-effect concentrations may also be estimated for categorizations of exposures for both continuous and dichotomous responses but these may depend on the arbitrary categories chosen. Respiratory function in miners exposed to coal dust is used to illustrate these methods.     

Modeling low birth weights using threshold regression: results for U. S. birth data

Babies born live under 2,500 g or with a gestational age under 37 weeks are often inadequately developed and have elevated risks of infant mortality, congenital malformations, mental retardation, and other physical and neurological impairments. In this paper, we model birth weight as a first hitting time (FHT) of a birthing boundary in a Wiener process representing fetal development. We associate the parameters of the process and boundary with covariates describing maternal characteristics and the birthing environment using a relatively new regression methodology called threshold regression. Two FHT models for birth weight are developed. One is a mixture model and the other a competing risks model. These models are tested in a case demonstration using a 4%-systematic sample of the more than four million live births in the United States in 2002. An extensive data set for these births was provided by the National Center for Health Statistics. The focus of this paper is on the conceptual framework, models and methodology. A full empirical study is deferred to a later occasion.     

Optimal Ordering Policies for Inventory Problems With Dynamic Information Delays

Information delays exist when the most recent inventory information available to the Inventory Manager (IM) is dated. In other words, the IM observes only the inventory level that belongs to an earlier period. Such situations are not uncommon, and they arise when it takes a while to process the demand data and pass the results to the IM. We introduce dynamic information delays as a Markov process into the standard multiperiod stochastic inventory problem with backorders. We develop the concept of a reference inventory position. We show that this position along with the magnitude of the latest observed delay and the age of this observation are sufficient statistics for finding the optimal order quantities. Furthermore, we establish that the optimal ordering policy is of state‐dependent base‐stock type with respect to the reference inventory position (or state‐dependent (s, S) type if there is a fixed ordering cost). The optimal base stock and (s, S) levels depend on the magnitude of the latest observed delay and the age of this observation. Finally, we study the sensitivity of the optimal base stock and the optimal cost with respect to the sufficient statistics.