变时滞控制系統的镇定性

本文首先建立一个变系数变时滞微分不等式。然后,利用此微分分等式研究具有变量时滞的控制系统的镇定问题,获得了判别系统镇定的简便充不了,准则。     

具有网络外部性的扩展Hotelling模型

将网络外部性引入线性运输成本下的Hotelling模型,研究了两家网络产品厂商首先选址,然后进行价格竞争的两阶段完全信息动态博弈问题,得到了厂商价格竞争均衡的存在性条件,推广了一般Hotelling模型的结论.由于网络外部性的存在,消费者效用是相互依赖的.网络产品的市场份额既是消费者选择的结果,又是消费者选择的依据.文章将交通流量分配技术和无穷维变分方法相结合,建立了刻画网络产品市场划分的模型——无穷维变分不等式,并研究了市场划分的存在性和唯一性问题.最后假定厂商定位在两端,分析了产品的网络外部性特征及单位运输成本对两个厂商竞争均衡情况的影响.     

Class inequality and meritocracy: a critique of Saunders and an alternative analysis

Saunders' recent work claiming that contemporary British society is to a large extent 'meritocratic' is criticized on conceptual and technical grounds. A reanalysis of the National Child Development Study data-set, used by Saunders, is presented. This reveals that while merit, defined in terms of ability and effort, does play a part in determining individuals' class destinations, the effect of class origins remains strong. Children of less advantaged class origins need to show substantially more merit than children from more advantaged origins in order to gain similar class positions. These differences in findings to some extent arise from the correction of biases introduced by Saunders; but there are also features of his own results, consistent with those reported in the reanalysis, which he appears not to have fully appreciated.     

关于Conte不等式的改进

利用Tchebycheff积分不等式改进了Conte不等式,构造了一些解析不等式。     

Conditional MSE-based discrimination of the sample mean and the post-stratification estimator in population sampling

Whenever a random sample is drawn from a stratified population, the post-stratification estimator $\tilde X$ usually is preferred to the sample mean $\tilde X$ , when the population mean is to be estimated. This is due to the fact that the variance of $\tilde X$ is asymptotically smaller than that of $\tilde X$ , while both estimators are asymptotically unbiased. However, this only holds looking at post-stratification unconditionally, when strata sample sizes are random. Conditioned on the realized sample sizes, the MSE of $\tilde X$ can be higher than that of $\tilde X$ which means that $\tilde X$ should be preferred to $\tilde X$ , even if it is biased. The conditional MSE difference of $\tilde X$ and $\tilde X$ is estimated, and using this estimation and its variance a heuristic test based on the Vysochanskiî-Petunin inequality is derived.     

Culture,Race, and the Economic Assimilation of Immigrants

The economic assimilation of European-origin immigrants is fairly rapid but selectively culture contingent; the economic assimilation of racial minority immigrants is less rapid and less culture contingent. Regression analysis of survey data examines occupational status and earnings effects of eight ethnic attachments among men and women in seven ethnic and racial minorities in mainstream and enclave employment in Toronto (N = 1792), controlling for foreign and domestically acquired human capital. Assimilationist pressures that the survey showed to be widely perceived may apply more to Europeans than to racial minorities. Economic assimilation is affected when foreignness is most pronounced: very selectively for European immigrants and universally for racial minorities treated as foreign, presumably based on skin color, regardless of specific culture, identity, behaviors, or network affiliations.     

农民工家庭收入和消费不平等:流动模式与代际差异

文章利用2008-2010年中国城乡劳动力流动调查数据(RUMIC),对农民工家庭收入不平等与消费不平等进行了测量和分解.研究结果显示:农民工消费不平等高于收入不平等,而家庭收入和消费不平等存在明显的流动模式差异与代际差异.收入来源和消费结构分解表明,劳动收入是收入不平等的主要来源,而消费不平等的主要来源则为食品、衣着和居住支出.对基尼系数进行的夏普里值分解进一步显示:流动模式差异对农民工家庭收入差距有较大影响,而代际差异是影响农民工家庭消费不平等的重要因素.     

Detection and Estimation of Block Structure in Spatial Weight Matrix

In many economic applications, it is often of interest to categorize, classify, or label individuals by groups based on similarity of observed behavior. We propose a method that captures group affiliation or, equivalently, estimates the block structure of a neighboring matrix embedded in a Spatial Econometric model. The main results of the Least Absolute Shrinkage and Selection Operator (Lasso) estimator shows that off-diagonal block elements are estimated as zeros with high probability, property defined as “zero-block consistency.” Furthermore, we present and prove zero-block consistency for the estimated spatial weight matrix even under a thin margin of interaction between groups. The tool developed in this article can be used as a verification of block structure by applied researchers, or as an exploration tool for estimating unknown block structures. We analyzed the U.S. Senate voting data and correctly identified blocks based on party affiliations. Simulations also show that the method performs well.