Oracle Inequalities for Convex Loss Functions with Nonlinear Targets

This article considers penalized empirical loss minimization of convex loss functions with unknown target functions. Using the elastic net penalty, of which the Least Absolute Shrinkage and Selection Operator (Lasso) is a special case, we establish a finite sample oracle inequality which bounds the loss of our estimator from above with high probability. If the unknown target is linear, this inequality also provides an upper bound of the estimation error of the estimated parameter vector. Next, we use the non-asymptotic results to show that the excess loss of our estimator is asymptotically of the same order as that of the oracle. If the target is linear, we give sufficient conditions for consistency of the estimated parameter vector. We briefly discuss how a thresholded version of our estimator can be used to perform consistent variable selection. We give two examples of loss functions covered by our framework.     

中国快递业发展的区域不平衡性测度研究

选取大陆31个省份2007—2014年样本数据,分别测算三区域、八区域分组下快递业发展的不平衡性及极化趋势。研究结果表明:中国快递业发展存在较强的区域不平衡性,且这种不平衡性还呈现不断加大趋势;东中西快递业发展不平衡性明显,总体呈现东部强中西部弱的特点,基尼系数分解结果显示,东中西组间差异为不平衡性贡献了70%以上的份额,同时东部和西部地区内部也存在相当程度的不平衡性;八区域不平衡性也非常明显,总体呈现沿海强内陆弱、东强西弱、南强北弱的基本格局,组间差异贡献了88%左右的份额,就区域内而言,南部沿海和西北地区不平衡性较强,东部沿海、长江中游及东北地区则较为平衡;三区域及八区域分组下快递业不平衡发展均呈现出不断增强的极化趋势。     

中国儿童基本机会多维不平等的综合测度研究

遵循国际规范,基于世界银行用于测度单一机会不平等的人类机会指数(Human Opportunity Index,HOI),借鉴最新的综合测度方法和多维机会指数(Multidimensional Human Opportunity Index,MHOI),首次对中国儿童的教育、医疗保险、安全饮水、卫生设施及家庭用电5种基本机会不平等进行综合测度。实证结果显示,2011年,中国7¹2岁儿童最少享有2种基本机会,所有基本机会全部享有的儿童不到60%。在所考虑的基本机会中,儿童卫生设施的覆盖率、公平性和HOI是最低的,其次是安全饮水;卫生设施和安全饮水的HOI表现出较大的地区和城乡差异。从而导致MHOI较大的地区和城乡差异;动态分析结果表明,近10多年来,中国儿童各种基本机会的覆盖率和公平性都得到了持续的改善,但各基本机会的HOI和MHOI仍存在较大的改善空间。这些量化结论具有一定的政策指导意义。     

新型职业农民:成长轨迹、影响因素及培育策略——基于19个省市39位新型职业农民生命历程的分析

通过对全国19个省市39位优秀新型职业农民的生命历程进行分析,发现其成长轨迹呈现出折勾型、倒梯型、V字型、阶梯型以及N字型五种类型,并且不同来源、不同世代的新型职业农民成长轨迹具有一定的差异性。究其原因,新型职业农民终身发展的动力支撑显得不足;新型职业农民的个体主观能动性得到了充分的发挥;政府扶持与引领作用有待继续加强;新型职业农民培育时机并未得到恰当的把握;影响新型职业农民成长的相关利益主体分布比较广泛。针对以上情况,提出新型职业农民的培育策略:强化政府主导力量,增强新型职业农民职业吸引力;吸收年轻优秀群体,壮大新型职业农民的新生力量;重视人地实际需求,把握新型职业农民培育的时机。     

保险素养、收入差异与农民商业保险参与

乡村振兴战略的实施激发了农民在“医、养、住、行”等方面对美好生活的追求,与之对应的各类保险保障需求也随之涌现。对保险素养影响农民商业保险参与的机理进行了阐释,并使用陕西省565户农户的调查数据,实证检验了保险素养对农民商业保险参与选择的影响,以及农民个人收入差异对保险素养影响其商业保险参与的调节效应。研究表明,保险素养会显著促使农民商业保险参与概率增加3.1%。此外,个人经济收入差异对保险素养促进农民商业保险参与并未发挥出调节作用,即提升个人收入水平并不会增强保险素养对农民商业保险参与的促进作用。因此,有必要采取提高农民保险素养、有针对性地开发设计符合农民诉求的保险产品等措施促进农民商业保险消费,进而促进商业保险在农村地区的发展。     

我国区域不均等:分解方法与实证分析

在对区域不均等度量指标及分解方法进行归纳性阐释的基础上,运用泰尔指数分析了我国自20世纪80年代中后期以来的区域不均等,并对我国区域差异中的城乡收入差距,东中西部农村地区的收入差距进行了分解。结果表明,在总的不均等中约70-80%的不均等来自城乡之间,只有20%-30%是由城市和农村内部引起的。东中西之间的不均等对总不均等的贡献大约只有20-30%,剩下的70-80%则归因于东中西各自内部不同省份之间的差距。     

Cultural capital or relative risk aversion? Two mechanisms for educational inequality compared1

In this paper we empirically examined two explanatory mechanisms for educational inequality: cultural reproduction and relative risk aversion, using survey data taken from secondary school pupils in Amsterdam. Cultural reproduction theory seeks to explain class variations in schooling by cultural differences between social classes. Relative risk aversion theory argues that educational inequalities can be understood by between-class variation in the necessity of pursuing education at branching points in order to avoid downward mobility. We showed that class variations in early demonstrated ability are for a substantial part cultural: cultural capital - measured by parental involvement in highbrow culture - affected school performance at the primary and secondary level. However, relative risk aversion - operationalized by being concerned with downward mobility - strongly affects schooling ambitions, whereas cultural capital had no effect. Thus, we conclude that 'primary effects' of social origin on schooling outcomes are manifested through cultural capital and not through relative risk aversion (in addition to other potential sources of class variations such as genetics). Relative risk aversion, and not cultural capital, affects schooling ambitions, which is relevant for our understanding of secondary effects.     

英语教学中的文化渗透

英语国家社会文化和汉语文化存在着很大差异,在英语教学中,不但要教会学生英语语言本身,也要传授给学生英语语言中所承载的社会文化内涵,使学生学到真正地道的英语,从而真正达到文化交流的目的。     

Driven by Inequalities: Exploring the Resurgence of Domestic Work in U.S. Cities

Domestic work, once the most common occupation for women around the globe, was thought to be well on its way to extinction at the end of the twentieth century. However, in the 1980s and 1990s, evidence began to appear that domestic work was in many places again becoming a growth occupation. My goal in this article is to examine the factors related to the recent expansion of domestic work in countries in the Global North, using the United States as a case study. I draw on U.S. Census data to document the resurgence of domestic work both nationally and in many large cities across the country, and then use multivariate analysis to compare rates of domestic work across these cities. The results indicate that rates of domestic work are highly related to variables measuring structural inequalities (racialization of the labor force, immigration, and economic polarization), while showing little relationship with variables measuring unmet care needs (care dependency ratios, female/maternal labor force participation, and availability of institutional care options). These findings underline the urgency of providing protections to domestic workers and point to the need for scholarship that better theorizes the relationships among unpaid care and different forms of paid care.