Sieve Estimation of Time-Varying Panel Data Models With Latent Structures

We propose a heterogeneous time-varying panel data model with a latent group structure that allows the coefficients to vary over both individuals and time. We assume that the coefficients change smoothly over time and form different unobserved groups. When treated as smooth functions of time, the individual functional coefficients are heterogeneous across groups but homogeneous within a group. We propose a penalized-sieve-estimation-based classifier-Lasso (C-Lasso) procedure to identify the individuals’ membership and to estimate the group-specific functional coefficients in a single step. The classification exhibits the desirable property of uniform consistency. The C-Lasso estimators and their post-Lasso versions achieve the oracle property so that the group-specific functional coefficients can be estimated as well as if the individuals’ membership were known. Several extensions are discussed. Simulations demonstrate excellent finite sample performance of the approach in both classification and estimation. We apply our method to study the heterogeneous trending behavior of GDP per capita across 91 countries for the period 1960–2012 and find four latent groups.     

A Novel Method to Calculate Mean Survival Time for Time-to-Event Data

In the analysis of time-to-event data, restricted mean survival time has been well investigated in the literature and provided by many commercial software packages, while calculating mean survival time remains as a challenge due to censoring or insufficient follow-up time. Several researchers have proposed a hybrid estimator of mean survival based on the Kaplan–Meier curve with an extrapolated tail. However, this approach often leads to biased estimate due to poor estimate of the parameters in the extrapolated “tail” and the large variability associated with the tail of the Kaplan–Meier curve due to small set of patients at risk. Two key challenges in this approach are (1) where the extrapolation should start and (2) how to estimate the parameters for the extrapolated tail. The authors propose a novel approach to calculate mean survival time to address these two challenges. In the proposed approach, an algorithm is used to search if there are any time points where the hazard rates change significantly. The survival function is estimated by the Kaplan–Meier method prior to the last change point and approximated by an exponential function beyond the last change point. The parameter in the exponential function is estimated locally. Mean survival time is derived based on this survival function. The simulation and case studies demonstrated the superiority of the proposed approach.     

论审美的中介作用

关于审美与艺术的关系,中外美学史上历来存在政教中心论与审美中心论之争.但两者都没有给审美找到在艺术中的正确位置.确立审美在艺术中的地位的两条途径是其一,为了包容不是以"美"为主要描写对象的各种现代艺术,应该把"美的艺术"扩大到"审美的艺术",但"美的艺术"仍是艺术的主流.其二,为了纠正审美中心论忽视审美与艺术中的其他因素以及审美与艺术之外的其他社会因索的联系这一理论错误,必须以审美中介论取代审美中心论.     

Differences in Child Health Across Rural,Urban, and Slum Areas: Evidence From India

The developing world is rapidly urbanizing, but an understanding of how child health differs across urban and rural areas is lacking. We examine the association between area of residence and child health in India, focusing on composition and selection effects. Simple height-for-age averages show that rural Indian children have the poorest health and urban children have the best, with slum children in between. With wealth or observed health environment held constant, the urban height-for-age advantage disappears, and slum children fare significantly worse than their rural counterparts. Hence, differences in composition across areas mask a substantial negative association between living in slums and height-for-age. This association is more negative for girls than boys. Furthermore, a large number of girls are “missing” in slums; we argue that this implies that the negative association between living in slums and health is even stronger than our estimate. The missing girls also help explain why slum girls appear to have a substantially lower mortality than rural girls, whereas slum boys have a higher mortality risk than rural boys. We estimate that slum conditions (such as overcrowding and open sewers), which the survey does not adequately capture, are associated with 20 % to 37 % of slum children’s stunting risk.     

技术嵌入与数字化商业模式创新——基于飞贷金融科技的案例研究

随着数字技术的快速发展,数字化商业模式创新成为企业竞争的利器,而技术嵌入是企业内化数字技术支撑数字化商业模式创新的重要策略.本文基于飞贷金融科技的创新实践开展纵向案例研究,探究技术嵌入对数字化商业模式创新的影响.研究发现:技术嵌入包含技术整合和技术开发,两种策略在企业发展过程中经历了不同形式的演变.其中,拼凑式技术整合更有利于商业模式要素创新,而协奏式技术整合更有利于商业模式架构创新.利用式技术开发更有利于商业模式渐进创新,而探索式技术开发更有利于商业模式颠覆创新.最终,案例企业的数字化商业模式呈现出一条"流程信息化→渠道平台化→产品数字化→技术产品化"的进阶式演化路径,数字化程度相应呈现"类抛物线"的演变规律.本研究丰富了数字化商业模式创新的相关理论,并为科技型企业构建数字化商业模式提供了实践启示.     

The Economic Assimilation of African Immigrants in the United States

This article examines the puzzle that the earnings of African immigrants do not match their high qualifications in terms of educational attainment. We apply cohort analysis to compare the economic assimilation patterns of black African immigrants with that of black non‐African immigrants. We find results that are consistent with the idea that the lower earnings of African immigrants are due to greater difficulty with skill transferability. Africans face substantially lower earnings at entry than black natives and black non‐African immigrants, although they close a substantial part of the initial earnings gap over time. Moreover, the earnings gap at entry has narrowed for recent cohorts; and Africans who migrate during childhood and those with no college education face no disadvantage. We also find similar patterns of assimilation in labour supply and participation in welfare programmes, which indicate that Africans face greater challenges at entry but assimilate at a faster rate.     

案例行动学习法——效率与效果的兼顾

案例教学法、行动学习法等主流商科情境教学模式虽在国内商学院中得到广泛的应用,但囿于使用过程中的资源限制、实施变形及方法本身的局限性,导致教学双方的反馈尚不尽如人意。本文介绍了一种全新的商科情境教学方法--"案例行动学习法"。论文应用建构主义理论探讨了"案例行动学习法"的基本原理,研究了该种方法的能力建构机理,分析了其成为工商管理主流情境教学方法的效率与效果的平衡机理,介绍了前期应用的效果。研究结果表明,"案例行动学习法"作为一种全新的工商管理情境教学方法,能够将案例教学与行动学习两种方法的优点有机结合在一起,具备在全国范围内推广的条件。     

Does Remittance Outflow Stimulate or Retard Economic Growth?

This article evaluates the association between remittance outflow (RMO) and economic growth in the Gulf Cooperation Council (GCC) countries. The results of this evaluation indicate that RMO Granger creates gross domestic product (GDP) per capita in three countries, namely, Bahrain, Oman and Saudi Arabia. Similarly, the results for causality from GDP per capita to RMO are significant for four countries, namely, Bahrain, Kuwait, Qatar, and Saudi Arabia. The findings differ from those of the household consumption model, stating that higher RMO will decrease economic activity. GDP per capita is the main determinant of RMO, suggesting that economic growth promises and encourages continuous RMO and vice versa. The adverse impact of RMO can be minimized by encouraging the local population to be productive in the private sector, as local productivity will reduce the huge influx of foreign workers and provide valuable local investment opportunities to lessen the amount being remitted.     

辽东第一山

大约4亿年前,千山山脉一带是一片海洋,到古生代末期开始形成陆地.经过漫长的地壳变化,到一千万年前,初步形成了千山地貌的基本轮廓.如今,它与长白山山脉相连,绵亘数百里,是整个辽东半岛的脊梁,辽河、鸭绿江分水岭.其中最峻秀的千朵莲花峰就矗立在鞍山城东南.清代文人姚元之有诗云:明霞为饰玉为容,山到辽阳峦嶂重.