Robust location estimation with missing data

In a missing data setting, we have a sample in which a vector of explanatory variables ${\bf x}_i$ is observed for every subject i, while scalar responses $y_i$ are missing by happenstance on some individuals. In this work we propose robust estimators of the distribution of the responses assuming missing at random (MAR) data, under a semiparametric regression model. Our approach allows the consistent estimation of any weakly continuous functional of the response's distribution. In particular, strongly consistent estimators of any continuous location functional, such as the median, L‐functionals and M‐functionals, are proposed. A robust fit for the regression model combined with the robust properties of the location functional gives rise to a robust recipe for estimating the location parameter. Robustness is quantified through the breakdown point of the proposed procedure. The asymptotic distribution of the location estimators is also derived. The proofs of the theorems are presented in Supplementary Material available online. The Canadian Journal of Statistics 41: 111–132; 2013 © 2012 Statistical Society of Canada     

Immigration,opportunity, and assimilation in a technology economy

Theory and Society - We examine access to institutions and opportunity for entrepreneurs in a rising tech economy. A significant proportion of entrepreneurs and CEOs of tech firms in the American...     

Erratum to: Mapping the Regional Divide in Europe: A Measure for Assessing Quality of Government in 206 European Regions

Social Indicators Research -     

Lightning Rods in the Local Moral Economy: Debating Unauthorized Migrants' Deservingness in Israel

Localized debates about who unauthorized migrants are and what they do, or do not, deserve unfold in a culturally specific register that is deeply charged with emotion and moral valuation. Structuring such debates are vernacular discursive frames that emerge from, and reflect, a common “local moral economy.” Taking Israel as case study, this article examines six elements of the country's local moral economy – biopolitical logic, historical memory, political emotion, popularized religion, an ideology of “fruitful multiplication,” and hasbara (“public diplomacy”/propaganda) – and explores their impact on public debates about unauthorized and irregular forms of migration. Here, as elsewhere, conventionalized distinctions that frame much migration scholarship – e.g. “economic” vs. “political” migrants, “migrant workers” vs. “refugees,” even the terms “authorized” and “unauthorized” themselves – bear but limited salience. Migration researchers who hope to influence local policy debates must recognize the weight and influence of local moral economies, and the chasms that divide vernacular from conventionalized frames. Achieving this sort of nuanced understanding is, at root, an ethnographic challenge.     

A Portfolio Approach to Procurement Contracts

The purpose of this paper is to develop a general framework for supply contracts in which portfolios of contracts can be analyzed and optimized. We focus on a multi‐period environment with convex contract, spot market, and inventory holding costs. We specialize the model to the case of a portfolio consisting of option contracts. We characterize the optimal replenishment policy and show that it has a simple structure. Namely, the use of every different option contract and the spot market is dictated by a modified base‐stock policy. In addition, we derive conditions to determine when an option is relatively attractive compared to other options or the spot market. Finally, we present our computational study, where we report the sensitivity of the results to the parameters of the model. Our experiments indicate that portfolio contracts not only increase the manufacturer's expected profit, but can also reduce its financial risk.     

Path dependent societal transformation: Stratification in hybrid mixed economies

Theory and Society -     

Swapping the Nested Fixed Point Algorithm: A Class of Estimators for Discrete Markov Decision Models

This paper proposes a new nested algorithm (NPL) for the estimation of a class of discrete Markov decision models and studies its statistical and computational properties. Our method is based on a representation of the solution of the dynamic programming problem in the space of conditional choice probabilities. When the NPL algorithm is initialized with consistent nonparametric estimates of conditional choice probabilities, successive iterations return a sequence of estimators of the structural parameters which we call K–stage policy iteration estimators. We show that the sequence includes as extreme cases a Hotz–Miller estimator (for K=1) and Rust's nested fixed point estimator (in the limit when K→∞). Furthermore, the asymptotic distribution of all the estimators in the sequence is the same and equal to that of the maximum likelihood estimator. We illustrate the performance of our method with several examples based on Rust's bus replacement model. Monte Carlo experiments reveal a trade–off between finite sample precision and computational cost in the sequence of policy iteration estimators.     

“刘易斯转折点”假象及其对“人口红利”释放的冲击

本文分析了当前普遍范围的用工荒是由于实际工资低于保留工资引起的农民工用脚投票结果。在此利用新家庭经济学单一模型理论分析这种经济行为是与简单单一个体预期效用最大化的经济行为相区别;农户以家庭为单位在金融资本及现代教育人力资本短缺的情况下通过家庭成员劳动力资本对外投资实施风险规避,在家庭内部实现收入分享,风险共担。这种经济行为带来的在工业制造和农业无法有效释放人口红利的结果,最终导致用工荒和环境负外部性以资本替代劳动的现代农业生产。     

在应对“用工荒”中推动企业转型升级

总结用工荒的基本特征,分析其产生的原因,并提出企业和政府联手应对用工荒的对策。认为企业要通过机械化和自动化降低用工依赖、提高效率和向低成本地区转移来化解用工高成本,变革企业管理减少员工流失。政府要通过加快区域产业布局调整、加强农民工职业技能培训、加快农业现代化建设提高用工供给、推动农民工与市民在住房保障等方面平权、优化农民工就业服务和劳动力市场建设、构建少取多予的财税扶持等措施,帮助企业应对用工荒,实现转型升级。