Model selection for stock prices data

The geometric Brownian motion (GBM) is very popular in modeling the dynamics of stock prices. However, the constant volatility assumption is questionable and many models with nonconstant volatility have been developed. In the papers [7 M.L. Esquível and P.P. Mota, On some auto-induced regime switching double-threshold glued diffusions, J. Stat. Theory Pract. 8 (2014), pp. 760–771. doi: 10.1080/15598608.2013.854184.[Taylor &; Francis Online] , [Google Scholar],12 P. P. Mota and M.L. Esquível, On a continuous time stock price model with regime switching, delay, and threshold, Quant. Financ. 14 (2014), pp. 1479–1488. doi: 10.1080/14697688.2013.879990.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]] the authors introduce a regime switching process where in each regime the process is driven by GBM and the change in regime is defined by the crossing of a threshold. In this paper we used Akaike's and Bayesian information criteria to show that the GBM with regimes provides a better fit than the GBM. We also perform a forecasting comparison of the models for two selected companies.     

Linearization of inequality indices in the design-based framework

Linearization methods are customarily adopted in sampling surveys to obtain approximated variance formulae for estimators of statistical functionals under the design-based approach. In the present paper, following the Deville [Variance estimation for complex statistics and estimators: linearization and residual techniques. Surv Methodol. 1999;25:193–203] approach stemming from the concept of design-based influence function, we provide a general result for linearizing a large family of population functionals which includes many of the inequality measures considered in social, economic and statistical studies, such as the Gini, Amato, Zenga, Atkinson and Generalized Entropy indices. The feasibility of our theoretical results is assessed by some simulation studies involving real and artificial data.     

初次分配、财政支出对居民收入差距的影响——基于动态面板GMM估计的实证分析

基于2007—2013年省级面板数据构建一个动态面板模型,利用差分矩估计和系统矩估计的方法对初次分配、财政支出结构对居民收入差距的影响进行实证研究.结果表明,现阶段初次分配的结构存在一定程度的不合理情况,会扩大居民收入差距,而农业、医疗卫生支出在财政支出中比重的提升是对收入差距缩小的有利因素.     

Spatial inequality and poverty among American children

National-level statistics often mask extreme spatial differentiation in child poverty. Using county-level data from the 1990 US decennial census summary tape file, we show that child poverty is distributed unevenly over geographic space. Child poverty is concentrated in counties in Appalachia, the Mississippi Delta, and the southern black belt. Child poverty rates are strongly influenced by the local industrial composition (e.g., agriculture and manufacturing), but the effects are largely indirect, operating primarily through reduced employment opportunities among adult workers. High county unemployment and underemployment rates contribute directly to children's economic deprivation, as well as indirectly by undermining the formation and stability of two-parent families. Our results highlight existing spatial differentiation and inequality in children's economic well-being, and provide a point of departure for additional research on the geography of child poverty.     

凸函数的一个定义及分析中的九个不等式

本文从凸函数的一个定义出发,得到了几个重要不等式,进而解决了一些不等式的证明。     

Does housework matter anymore? The shifting impact of housework on economic inequality

In recent years, American women’s housework time has declined while American men’s housework time has risen. We examine how these changes have affected economic inequality in the United States. Using time-diary data from the Time Use in Economic and Social Accounts, 1975–1976 (N = 1,484) and the American Time Use Survey, 2003 (N = 5,534), we value adults’ housework using two alternative methodologies and assess its influence on households’ real access to goods and services in both years. Results suggest that housework reduces economic inequality in both years. But, between 1975–1976 and 2002–2003, overall economic inequality rose largely because of the growing wage inequality and also, in part, because of growth in housework inequality. Socio-demographic change partially inhibited the overall growth in economic inequality.

“98房改”的历史与社会影响：基于利益分化的视角

自1998年全面停止实物分房这一具有里程碑意义的改革开始,中国房地产业得到快速发展,城镇居民的住房条件得到了极大的改善,但住房利益分化也日益突出。“98房改”通过内部市场的方式在将计划经济时期由单位制所决定的住房利益差异固化,并一定程度上使之在住房改革过程中以及改革后的房地产市场中得以放大。尽管从市场角度理解住房利益差异是不可忽略的视角,但历史回溯表明,住房政策及其变动过程本身对利益分化的影响同样不可忽视,并且这种影响也会因为政策设置缺乏预见性而持续作用于改革之后的市场当中。     

不同教育融资体制下的人力资本积累

本文首先分析了我国人力资本的变化规律,然后依此建立了人力资本积累的世代交叠模型。模型中引入了不确定性因素,以全社会人力资本分布作为考察对象,重点阐述了市场和公共教育体制下人力资本积累的内生决定以及教育融资体制改革问题。人力资本积累的不确定性和教育支出的产出弹性,内生决定了人力资本的积累路径和市场教育体制的改革方向。     

The Associations Between Socioeconomic Status,Caregivers' Depressive Symptoms,Children's Health‐Promoting Behavior,and Children's Physical Health: A Mediation Model

The aim of this study was to examine the mediating effects of children's health‐promoting behaviors on the association between socioeconomic status, caregivers' depressive symptoms, and children's physical health outcomes. We used the first wave of “Seoul Education and Health Welfare Panel.” Data were collected from 820 fourth‐grade elementary and first‐year middle school students and their caregivers using self‐administered surveys. Structural equation modeling was employed to analyze the mediating effects of health‐promoting behaviors. Bias‐corrected bootstrap confidence intervals were used to test the mediating effect. The results showed that both low socioeconomic status and caregivers' depressive symptoms were negatively associated with a child's health‐promoting behaviors. Children's health‐promoting behaviors were positively associated with physical health. However, children's physical health was not significantly associated with socioeconomic status but was marginally associated with caregivers' depressive symptoms. We found that children's health‐promoting behaviors significantly mediated associations between both socioeconomic status and children's physical health and between caregivers' depressive symptoms and children's physical health. Based on the findings, we suggest the development and implementation of school‐based, health‐enhancement programs as a means to improve the general health of all children and to reduce health inequalities.     

Labor Mobility Without Pension Portability: Migrant Workers’ Endangered Pension Entitlement in China

This paper investigates migrant workers’ endangered pension entitlement in China from a perspective of political economy. The decentralized pension governance structure in China led to limited portability of the urban pension program. The movement of migrant workers challenges this decentralized governance structure, and have also produced clear winner and loser provinces in the pension program. This study argues that the interests of migrant‐receiving provinces, the winners, became a major obstacle in reforms that sought to address the pension portability problem. The migrant workers’ pension issue has in fact contributed to inter‐regional welfare inequality. This resulting inter‐regional inequality makes any central government's plan on centralizing the pension program a challenging task.