Assortative mating among unmarried parents: Implications for ability to pay child support

Assortative mating is of interest to both theoretical and applied social scientists. Previous research is based almost entirely on married couples and parents. In this paper we use data from the NSFG to examine assortative mating among unmarried parents in the US and to examine the robustness of estimates of nonresident fathers' income based on assortative mating assumptions. We find that never married parents are similar, though not identical, to married parents in their choice of partners. White unmarried women are much more likely to have a child with a non-white male than white married women. On the other hand, unmarried women are more likely than married women to have a child with a more educated male. Received: 31 May 2000/Accepted: 2 January 2001     

回收模式相异的零售商主导型闭环供应链竞争模型研究

随着经济全球化的推进，同行业竞争已逐渐由企业间的竞争转化为供应链间的竞争。在此背景下，本文围绕MR、MT和RT三种相异的回收模式组合，构建了两条零售商主导型闭环供应链的竞争博弈模型，运用逆向归纳法得到三种回收模式组合下各条链的均衡价格、回收率、渠道成员利润、单条链利润与双链总利润，然后结合链间竞争强度将不同回收模式组合的结果进行比较，研究表明：（1）在三种回收模式组合下，链间竞争强度的增加将使批发价、零售价与回收率均提高，市场需求量增大，各渠道成员的收益均得到改善，但却损害了消费者利益；（2）MR与MT组合下四条链的产品售价、单链回收率、制造商利润、零售商利润与单链总利润排序均与链间竞争强度无关，而RT组合两条链的变量均衡解、利润与MR、MT组合的数量关系与链间竞争强度密切相关；（3）对于两条竞争性闭环供应链的任一条链，若其竞争链是制造商回收链（零售商回收链），则在选择相异回收模式时，从整条链利润视角其应形成零售商回收链（制造商回收链）；若其竞争链是第三方回收链，当双链竞争不是极为剧烈时，其应形成制造商回收链，否则应形成零售商回收链；（4）当链间竞争较平稳时，MR组合的双链总利润优于MT组合和RT组合；随着双链竞争强度的增加，RT组合的双链总利润将依次超过MT组合与MR组合；当链间竞争特别激烈时，MR组合甚至低于MT组合。故链间竞争强度的增加对RT组合两条链具有最显著的积极影响，而对MR组合的影响则较为有限。本文研究不仅拓展了闭环供应链竞争理论，而且能够为现实中处于链与链竞争环境下的企业选择合理的回收模式提供理论支持。     

The Best Predictors of Survival: Do They Vary by Age,Sex, and Race?

We consider a broad set of variables used by social scientists and clinicians to identify the leading predictors of five‐year survival among American adults. We address a question not considered in earlier research: Do the strongest predictors of survival vary by age, sex or race/ethnicity? The analysis uses hazard models with 30 well‐established predictors to examine five‐year survival in the National Health and Nutrition Examination Survey. We find that the simple measure of self‐assessed health and self‐reported measures of functional ability and disability are the strongest predictors in all demographic groups, and are generally ranked considerably higher than biomarkers. Among the biomarkers, serum albumin is highly ranked in most demographic groups, whereas clinical measures of cardiovascular and metabolic function are consistently among the weakest predictors. Despite these similarities, there is substantial variation in the leading predictors across demographic groups, most notably by race and ethnicity     

Beyond Self‐Reports: Changes in Biomarkers as Predictors of Mortality

The proliferation of biosocial surveys has increased the importance of weighing the costs and benefits of adding biomarker collection to population‐based surveys. A crucial question is whether biomarkers offer incremental value beyond self‐reported measures, which are easier to collect and impose less respondent burden. We use longitudinal data from a nationally representative sample of older Taiwanese (aged 54+ in 2000, examined in 2000 and 2006 with mortality follow‐up through 2011) to address that question with respect to predicting all‐cause mortality. A summary measure of biomarkers improves mortality prediction (as measured by the area under the receiver operating characteristic curve) compared with self‐reports alone, but individual biomarkers perform better than the summary score. We find that incorporating change in biomarkers over a six‐year period yields a small improvement in mortality prediction compared with one‐time measurement. But, is the incremental value worth the costs?     

基于批量流的多阶段生产系统的优化问题研究

考虑一个多阶段生产系统,在每个阶段上生产批量被分成若干个子批量进行加工,子批量可以相等也可以不相等,同时每个阶段上在相邻子批量之间可以有空闲。每个阶段上子批量的数目可以不相等。文中首先以系统总变动成本为目标函数对这样一个系统建立对应的模型,提出了求解这一问题的启发式方法,通过数值算例验证了这一方法的有效性。此外,还讨论了重启成本、空闲成本和对应于子批量的调整成本对系统总变动成本、生产批量以及子批量数目的影响。     

考虑双向主导相异的闭环供应链物流策略与补贴机制研究

目前,闭环供应链研究均是在正向和逆向主导企业为同一企业的条件下进行的,然而正向供应链中企业重视产品质量,逆向供应链中企业重视回收渠道,况且正向供应链中的物流策略并不一定适合逆向供应链。基于此,将供应链主导模式分为正向制造商主导和逆向销售商主导,物流策略分为正向物流策略和逆向物流策略。通过构建模型,运用博弈论理论,探讨了不同闭环供应链的定价策略、补贴机制和供应链稳定性,得到了供应链主导企业通过选择物流策略和补贴机制来实现供应链稳定性的条件。     

多属性决策的组合赋权方法研究

提出了多属性决策组合赋权的一种线性目标规划方法,该法把主观和客观两类权重信息相结合,既能充分利用客观信息,又尽可能地满足决策者的主观愿望,且具有思路清晰、简洁实用、易于计算机上实现等特点。最后通过算例说明了方法的可行性和有效性。     

供应链中基于Stackelberg博弈的EOQ模型

本文考虑一个含有一个供应商和一个零售商的整个供应链中,供应商在链中占据垄断地位,他不仅拥有零售商相关的成本信息,还有交货时间的决策权。在这种条件下,本文研究零售商和供应商的最优交货时间和最优订货周期问题,给出了近似的最优解,并用数值方法分析了对交货时间的控制给供应商和给零售商带来的和益处和损失。     

基于粗糙集的不一致信息系统规则获取方法

本文提出了一种基于粗糙集的既能学习决策性分类规则也能学习非决策性分类规则的方法,目的是获得更一般、更可靠的分类规则,并设计了相应的算法。算法的基本思想是允许用户在学习分类过程中指定三个参数:最小的支持度、分类规则必须满足的一致度、覆盖度,据此推导出满足参数要求的规则。最后将该方法应用于一个算例中,提取了满足给定参数阈值的规则。该方法在处理噪音数据及大型数据库分析等方面具有较强功能。     

基于DEA的新证券上市定价基准与投资价值研究

本文针对新证券上市定价存在的问题,提出了基于DEA的新证券上市价值实现程度评价和基准价格评估模型及相应的研判准则,并对我国基金市场进行了实证检验,结果表明这一方法是可行的。