Composite quantile regression for varying-coefficient single-index models

ABSTRACT

The varying-coefficient single-index model (VCSIM) is a very general and flexible tool for exploring the relationship between a response variable and a set of predictors. Popular special cases include single-index models and varying-coefficient models. In order to estimate the index-coefficient and the non parametric varying-coefficients in the VCSIM, we propose a two-stage composite quantile regression estimation procedure, which integrates the local linear smoothing method and the information of quantile regressions at a number of conditional quantiles of the response variable. We establish the asymptotic properties of the proposed estimators for the index-coefficient and varying-coefficients when the error is heterogeneous. When compared with the existing mean-regression-based estimation method, our simulation results indicate that our proposed method has comparable performance for normal error and is more robust for error with outliers or heavy tail. We illustrate our methodologies with a real example.     

样本选择参数分位回归模型及其在工资分布分解中的应用

在工资差距分解问题中,研究者经常会遇到样本选择偏差问题,直接忽略会导致最终估计结果产生严重偏差,同时在众多工资差距分解方法中,相比于均值分解,分布分解方法更受研究者青睐。针对参数分位回归,本文首次提出可加形式与非可加形式的样本选择参数分位回归（SSPQR）模型,并基于这两类样本选择参数分位回归模型给出修正样本选择偏差后的参数分位回归工资差距分布分解方法。运用上述方法及已有的工资分布分解方法,借助CHNS2015年度城镇数据,本文研究了我国城镇男女工资差距及差距分解问题,得出以下结论：①男女工资差距主要来源是性别歧视问题;②经过样本选择偏差修正后,实际的工资差距更大,歧视问题更严重;③男女工资差距程度在不同分位点上结果不同,换句话说,我们不能简单地仅从平均水平来判断工资差距程度;④与其他已有方法计算结果比较发现,SSPQR计算的工资差距程度更大。     

小额信贷经理人愿意扶贫吗？——基于西北地区贫困县152位信贷经理人的经验分析

基于西北5省15个国家级贫困县152位信贷经理人的问卷调查,分析了小额信贷经理人的扶贫意愿、行为以及影响因素。经验研究结果表明：在调研的国家级贫困县中,尽管近六成小额信贷经理人向贫困户发放过贷款,但业务量总体较少,具有信贷扶贫意愿的不到2成;性别、教育背景、收入满意度、信贷决策自主性、放贷任务以及是否完成任务对信贷扶贫业务有显著影响;性别和信贷自主权对扶贫意愿具有显著影响。由此,在信贷扶贫项目选择信贷经理人时,采取差异化策略,有序放松信贷自主权,加强扶贫效果考核,对提高金融扶贫绩效会起到积极的作用。     

民间组织参与我国贫困治理的角色及行动策略

民间组织是参与贫困治理的重要社会力量。在我国扶贫开发进程中,民间组织在贫困治理中扮演了扶贫资源有益补充、践行微观贫困治理理念/技术、专业扶贫服务供给等多种角色。民间组织的贫困治理行动是民间组织汲取各类资源并将其传递到扶贫对象的过程。在大扶贫格局中,民间组织扶贫资源汲取已由传统的社会领域延伸至政府部门和市场领域,形成了慈善捐助、政府购买扶贫服务、市场化运作（社会企业）等多种扶贫资源汲取策略。相应的,主要形成了项目机制、市场机制两种扶贫资源传递策略。项目机制的运用表明了民间组织在分化发展的过程中扶贫资源传递的整合,以及民间组织与政府部门协同推进贫困治理的制度化和规范化。市场机制（社会企业）是民间组织扶贫行动的策略创新,对民间组织独立实施贫困治理具有重要意义。     

竞争市场中生产与碳交易策略

在碳排放约束下,利用动态古诺模型,分析厂商如何优化产量、交易碳排放权的规模、净化节约额以实现利润最大化的问题,得到相应的均衡量和各阶段最优量,并给出竞争市场中的企业减排策略以及政府的行为和碳排放权价格对企业减排策略的影响,阐述在竞争市场中减排和碳排放权交易的运行机制。研究发现: 双寡头竞争市场中存在均衡状态;在减排率较低时,制造上获得最高利润,而企业追求过高的减排率将会导致过分依赖碳减排市场而获得较低的利润;制造商应该适时低价购入过量碳排放权,而在高价时卖出多余的碳排放权,以充分利用碳排放权市场以增加利润降低成本;制造商的利润会随着政府碳排放权分配系数的增加而增加。     

减排约束下中国天然气供需安全评价:2006-2014年

为准确把握中国天然气供需安全状态,以2006-2014年的数据为样本,在模糊隶属度函数量化指标值的基础上,运用层次分析法(AHP)和熵值法确定指标权重,基于线性加权和函数计算均方根进行综合评价。结果表明:(1)中国天然气供需安全指数呈现"N形"波动,2006-2007年天然气供需安全指数上升。2007-2013年天然气供需安全指数年均下降1.7979。2013年以来天然气供需安全指数开始回升,天然气供需安全压力有所缓解。(2)天然气供应安全指数从2006年的17.5914下降到2013年的0.1556,峰谷差17.4359。天然气需求安全指数呈现"W形"波动。天然气市场安全指数相对稳定,2013年以来略有上升,天然气市场风险逐年下降。(3)天然气供需安全很大程度上取决于天然气供应是否安全。因此,建议从确保天然气稳定供应、提高天然气使用效率和降低市场风险方面采取措施,维护天然气供需安全。     

An Empirical Process View of Inverse Regression

A common approach taken in high‐dimensional regression analysis is sliced inverse regression, which separates the range of the response variable into non‐overlapping regions, called ‘slices’. Asymptotic results are usually shown assuming that the slices are fixed, while in practice, estimators are computed with random slices containing the same number of observations. Based on empirical process theory, we present a unified theoretical framework to study these techniques, and revisit popular inverse regression estimators. Furthermore, we introduce a bootstrap methodology that reproduces the laws of Cramér–von Mises test statistics of interest to model dimension, effects of specified covariates and whether or not a sliced inverse regression estimator is appropriate. Finally, we investigate the accuracy of different bootstrap procedures by means of simulations.     

Uncertainty Analysis for Functional Computer Output: A Simulation Study in Inverse Problems

Computer models with functional output are omnipresent throughout science and engineering. Most often the computer model is treated as a black-box and information about the underlying mathematical model is not exploited in statistical analyses. Consequently, general-purpose bases such as wavelets are typically used to describe the main characteristics of the functional output. In this article we advocate for using information about the underlying mathematical model in order to choose a better basis for the functional output. To validate this choice, a simulation study is presented in the context of uncertainty analysis for a computer model from inverse Sturm-Liouville problems.     

Probability Generating Function Based Jeffrey's Divergence for Statistical Inference

Statistical inference procedures based on transforms such as characteristic function and probability generating function have been examined by many researchers because they are much simpler than probability density functions. Here, a probability generating function based Jeffrey's divergence measure is proposed for parameter estimation and goodness-of-fit test. Being a member of the M-estimators, the proposed estimator is consistent. Also, the proposed goodness-of-fit test has good statistical power. The proposed divergence measure shows improved performance over existing probability generating function based measures. Real data examples are given to illustrate the proposed parameter estimation method and goodness-of-fit test.     

Functional Partial Linear Single‐index Model

This paper deals with the problem of predicting the real‐valued response variable using explanatory variables containing both multivariate random variable and random curve. The proposed functional partial linear single‐index model treats the multivariate random variable as linear part and the random curve as functional single‐index part, respectively. To estimate the non‐parametric link function, the functional single‐index and the parameters in the linear part, a two‐stage estimation procedure is proposed. Compared with existing semi‐parametric methods, the proposed approach requires no initial estimation and iteration. Asymptotical properties are established for both the parameters in the linear part and the functional single‐index. The convergence rate for the non‐parametric link function is also given. In addition, asymptotical normality of the error variance is obtained that facilitates the construction of confidence region and hypothesis testing for the unknown parameter. Numerical experiments including simulation studies and a real‐data analysis are conducted to evaluate the empirical performance of the proposed method.