多维框架下的中国不平等测度及分解

新时期中国不平等问题表现出新的特征,传统的单一维度不平等已经无法反映现今不平等问题的多维性特点。本文将量化不平等的视角从一维拓展到多维,基于单维不平等合成多维不平等等三种方法测度了收入、教育、医疗多维不平等程度,同时还完成了对多维不平等指数的分解。结果表明,中国社会整体的多维不平等程度逐步加深,收入不平等依旧是贡献程度最大的单维不平等。本文得到的一个重要政策建议是认识和解决不平等问题必须注重单一维度和多维相结合;收入差距缩小并不代表多维不平等的同步改善,政府应该通过政策手段来进一步发挥在民生领域,特别是教育、医疗领域的调控作用。     

与收入相关的健康不平等扩大了吗

引致健康不平等原因在很大程度上可追溯到收入不平等。本文利用中国营养与健康调查数据,采用建立在追踪调查样本上的集中系数,对1990-2006年间与收入相关健康不平等进行了测度和分解。结果显示：（1）城市和农村都存在着亲富人的健康不平等且累积效应不断深化,初始收入不平等是健康不平等加剧的重要原因;（2）居民平均健康水平有所降低,穷人的健康变动度大于富人,农村的健康不平等大于城市;（3）农村收入不平等扩大带来了健康不平等上升,而城市相关医疗卫生服务水平的提高,使收入不平等扩大对健康不平等的负效应有所减弱。因此,提升公共服务均等化水平、缩小城乡健康差距,是缓解健康不平等的有效途径。     

教育与收入分配差距：中国农村的经验研究

 教育作为人力资本积累的主要手段,对收入分配有着重要的影响。本文借鉴Beach提出的分位数法构建时间系列模型,利用中国农村1993-2007年的数据,从受教育水平和教育不平等程度两个方面考察了教育与农村居民收入分配之间的关系。研究表明,在中国农村,教育的不平等会加剧收入的不平等,或者说教育的均化会改善收入分配状况;平均受教育年限与收入不平等之间表现为正相关关系。这表明,当前我国农村整体教育水平仍然落后,教育对农村居民收入分配的影响模式仍处于倒U型的左边。上述结论对农村的收人分配政策与教育政策的制定和调整具有重要的含义。     

城镇居民收入不平等分解研究

 本文利用国家统计局城镇住户调查数据对2002—2007年城镇居民收入不平等进行了研究。研究发现：○1基尼系数先上升后下降,2002、2004和2007年的基尼系数分别为0.342、0.361和0.349。○2房地产和资本市场扩大城镇居民收入不平等的作用日益增强,财产性收入已成为仅次于工资及补贴收入、公共转移支付净收入影响收入不平等的第三大分项收入,2007年的贡献率约为7.3%。○3更高的投资门槛以及持续上涨的房价使得房产投资比金融资产投资更能扩大城镇居民收入差距。     

Inequality and negative income

Summary This note deals with some problems in the measurement of inequality when negative incomes are allowed. A new axiom is defined, called the Greatest Gets More axiom. Using this axiom it can be shown that the properties of some inequality measures depend on whether there are negative incomes or not. In this paper, for the intermediate measures of Eichhorn and the centrist inequality measures of Kolm a threshold value is given above which the Greatest Gets More axiom holds. I am indebted to two anonymous referees for their helpful comments.     

对外贸易与国内收入差距：基于全球125个国家的实证分析

 本文利用全球125个国家的统计数据,分所有国家、发达国家、发展中国家、亚洲发展中国家四个层面,实证分析了进出口贸易对世界各国以及不同类型国家国内收入差距的影响程度、作用以及在影响收入差距所有因素中的地位。研究结果表明：（1）对于所有国家来说,进口和出口对国家内部的收入差距影响系数较小且不显著,金融发展程度因素和高等教育因素是影响国家内部收入差距的重要因素。（2）对于发达国家来说,进口和出口因素是影响国家内部收入差距的主要因素,进口因素和出口因素的影响系数比较大且都比较显著,进口增加有利于扩大收入差距,出口增加有利于缩小收入差距。经济自由度也是影响发达国家国内收入差距的主要因素。（3）对于所有发展中国家来说,进口和出口因素对国家内部收入差距的影响系数较小且都不显著,只有外商直接投资因素和基础教育因素具有显著性。（4）对于亚洲发展中国家来说,进出口贸易因素是影响亚洲发展中国家国内收入差距的重要因素,进口有利于缩小收入差距,出口扩大了收入差距,与所有发展中国家的考察结果相比,进出口贸易对亚洲发展中国家国内收入差距的影响程度更大,且更加显著。     

Estimating and testing generalized linear models under inequality restrictions

We consider maximum likelihood estimation and likelihood ratio tests under inequality restrictions on the parameters. A special case are order restrictions, which may appear for example in connection with effects of an ordinal qualitative covariate. Our estimation approach is based on the principle of sequential quadratic programming, where the restricted estimate is computed iteratively and a quadratic optimization problem under inequality restrictions is solved in each iteration. Testing for inequality restrictions is based on the likelihood ratio principle. Under certain regularity assumptions the likelihood ratio test statistic is asymptotically distributed like a mixture of χ², where the weights are a function of the restrictions and the information matrix. A major problem in theory is that in general there is no unique least favourable point. We present some empirical findings on finite-sample behaviour of tests and apply the methods to examples from credit scoring and dentistry.     

M-quantile models with application to poverty mapping

Over the last decade there has been growing demand for estimates of population characteristics at small area level. Unfortunately, cost constraints in the design of sample surveys lead to small sample sizes within these areas and as a result direct estimation, using only the survey data, is inappropriate since it yields estimates with unacceptable levels of precision. Small area models are designed to tackle the small sample size problem. The most popular class of models for small area estimation is random effects models that include random area effects to account for between area variations. However, such models also depend on strong distributional assumptions, require a formal specification of the random part of the model and do not easily allow for outlier robust inference. An alternative approach to small area estimation that is based on the use of M-quantile models was recently proposed by Chambers and Tzavidis (Biometrika 93(2):255–268, 2006) and Tzavidis and Chambers (Robust prediction of small area means and distributions. Working paper, 2007). Unlike traditional random effects models, M-quantile models do not depend on strong distributional assumption and automatically provide outlier robust inference. In this paper we illustrate for the first time how M-quantile models can be practically employed for deriving small area estimates of poverty and inequality. The methodology we propose improves the traditional poverty mapping methods in the following ways: (a) it enables the estimation of the distribution function of the study variable within the small area of interest both under an M-quantile and a random effects model, (b) it provides analytical, instead of empirical, estimation of the mean squared error of the M-quantile small area mean estimates and (c) it employs a robust to outliers estimation method. The methodology is applied to data from the 2002 Living Standards Measurement Survey (LSMS) in Albania for estimating (a) district level estimates of the incidence of poverty in Albania, (b) district level inequality measures and (c) the distribution function of household per-capita consumption expenditure in each district. Small area estimates of poverty and inequality show that the poorest Albanian districts are in the mountainous regions (north and north east) with the wealthiest districts, which are also linked with high levels of inequality, in the coastal (south west) and southern part of country. We discuss the practical advantages of our methodology and note the consistency of our results with results from previous studies. We further demonstrate the usefulness of the M-quantile estimation framework through design-based simulations based on two realistic survey data sets containing small area information and show that the M-quantile approach may be preferable when the aim is to estimate the small area distribution function.     

机会不平等的衡量：参数测度法的应用与改进

本文在考虑不可测环境和努力变量的影响,以及处理环境和努力变量相关性的基础上,改进机会不平等的参数测度法,并运用这一方法对中国居民收入分配的机会不平等程度进行数量测度。结果显示：样本期间,机会不平等占收入不平等的比例平均达到29%左右;分解结果显示,可测环境变量导致的机会不平等占收入不平等的比重维持在27%左右,不可测环境变量对收入不平等的贡献平均而言只有2%左右。此外,家庭教育背景差异、区域差距、城乡差距和性别歧视构成了现阶段中国居民机会不平等的主要来源。本文认为,为降低中国居民收入的机会不平等程度,政府应对因外部环境不利而陷入贫困的居民进行救济和补偿,为弱势群体依靠自己的努力取得成功创造条件和提供平台。     

潜在流动性约束与城镇家庭消费

笔者认为,收入不平等与家庭消费的关系与信贷约束程度以及家庭社会地位偏好有关。住房是典型的地位性商品,收入差距扩大时,人们为了维持或提高现有的相对地位会努力改善居住条件,住房攀比最终会导致全社会住房面积标准提高和房价上涨。在信贷缺乏的环境中,购房标准提高和房价上涨意味着家庭未来遭遇流动性约束的风险加大,为此,家庭在增加购房预算的同时会抑制日常消费。利用2010年、2012年和2014年的微观跟踪调查数据所做的实证分析支持了我们的观点：（1）周围人群的住房面积的扩大,会促使家庭选择购买更大的房子。并且,攀比效应对住房需求的刺激作用明显大于房价上涨对住房需求的抑制作用。（2）家庭平均住房面积扩大和房价上涨都与收入不平等引发的住房攀比有关。（3）收入不平等对城镇家庭消费皆有拉动作用和抑制作用。（4）潜在流动性约束对家庭消费的抑制作用与家庭地位等级的高低有关。     

Admissible Linear Predictors in the Superpopulation Model with Respect to Inequality Constraints

Admissibility of linear predictors of the linear quantity Qy is investigated under a general linear regression superpopulation model with some inequality constraints. The relation between admissible homogeneous and inhomogeneous linear predictors is characterized. Further, necessary and sufficient conditions for a linear predictor to be admissible in two cases of inequality constraints in the classes of homogeneous and inhomogeneous linear predictors are given, respectively.     

收入波动与基尼系数:关于收入不平等的一个讨论

 本文建立了一个考察收入波动与基尼系数关系的模型,并通过计算机模拟实验证实：给定任何终生收入不平等状况,收入波动性增加都将导致各期的基尼系数增大。即,在终生收入不平等状况不变的情况下,各期的基尼系数也可因收入波动性增加而增大。考虑到我国经济转轨进程中家庭收入波动性日益增加的事实,则本文结论意味着,仅以基尼系数为判断标准很可能在一定程度上高估我国的家庭收入不平等状况。     

随机效应半参数logit模型的惩罚似然估计研究

 在颇具争议的收入差距和健康关系研究中,为了降低可能存在的模型设定和遗漏变量偏误,本文提出了随机效应半参数logit模型,其中非参数的设定还可用于数据的初探性分析。随后本文提出了模型非参数和参数部分的估计方法。这里涉及的难点是随机效应的存在导致似然函数中的积分没有解析式,而非参数的存在更加大了估计难度。本文基于惩罚样条非参数估计方法和四阶Laplace近似方法建立了惩罚对数似然函数,其最大化采用了Newton_Raphson近似方法。文章还建立了惩罚样条中重要光滑参数的选取准则。模型在收入差距和健康实例中的估计结果表明数据支持收入差距弱假说,且非参数估计结果表明其具有U型形式,与实例估计结果的比较指出本文提出的估计方法是较准确的。     

外资进入与国内工资差异：基于工业行业面板数据的联立估计

 本文通过内生化熟练劳动力的相对工资与相对供给,建立两方程联立估计模型,利用1999-2006年我国36个工业行业数据实证考察了外资对我国工资不平等的影响。以科技人员相对工资作为熟练劳动力的代理指标,研究结果表明,外资进入一方面会通过技术外溢渠道促进我国内资企业偏向熟练劳动力的技术进步、从而扩大我国的工资不平等,另一方面其较高的劳动报酬会吸引更多的熟练劳动力流向外资企业、从而减少我国内资企业熟练劳动力的相对供给,进而进一步扩大我国的工资不平等。文章最后对估计结果的稳健性进行了较为细致的检验,检验结果表明本文的主要估计结果是稳健的。     

人口老龄化与代际财政不平等——基于代际账户核算法的模拟分析

本文采用代际账户核算方法,模拟测算了中国“现存代”和“未来代”的净税收负担值,探讨人口老龄化与代际财政不平等的关系。结果显示：如果保持当前财税制度和社会保障体制不变,未来代的净税收负担要明显高于现存代,中国存在较为严重的代际财政不平等问题,而且未来人口老龄化的进程越快,代际财政不平等程度就越高;但是,老龄化与代际财政不平等的关系还取决于劳动生产率和折现率的变化,折现率越低以及劳动生产率的增长率越高,将会缓解老龄化对代际财政不平等的冲击。据此本文认为,应逐步放开生育政策、延长退休年龄、提高劳动生产率,以改善老龄化背景下的代际财政失衡状况。     

A Unified Approach to Likelihood Inference on Linear Inequality Constraints in Contingency Tables

In contingency table analysis, a likelihood ratio test for linear inequality constraints is discussed. The restriction condition considered in this article is much more general than usual stochastic order restriction conditions. Asymptotic property of test statistic is shown. Simulation study is conducted to compare the empirical power and size performed via the proposed method and others. Several real data sets are used to illustrate our theoretical result. The idea used in this article can be applied to test the problems with nonlinear inequality constraints.     

Trends in inequality in infant mortality in the north of England, 1921–1973, and their association with urban and social structure

Summary.  The paper analyses a time series of infant mortality rates in the north of England from 1921 to the early 1970s at a spatial scale that is more disaggregated than in previous studies of infant mortality trends in this period. The paper describes regression methods to obtain mortality gradients over socioeconomic indicators from the censuses of 1931, 1951, 1961 and 1971 and to assess whether there is any evidence for widening spatial inequalities in infant mortality outcomes against a background of an overall reduction in the infant mortality rate. Changes in the degree of inequality are also formally assessed by inequality measures such as the Gini and Theil indices, for which sampling densities are obtained and significant changes assessed. The analysis concerns a relatively infrequent outcome (especially towards the end of the period that is considered) and a high proportion of districts with small populations, so necessitating the use of appropriate methods for deriving indices of inequality and for regression modelling.     

基于SNA生产观的生产负担不均等测度与分解

 基于SNA生产观，本文讨论了总生产负担、SNA生产负担和非SNA生产负担的不均等规律。理论分析表明，三类生产负担的具体分布取决于个人或家庭的生产时间分配模式，个人受实际SNA报酬率和总生产时间的影响较大，而家庭往往视性别因素为基本决策前提。本文据此实际测度了我国居民各类生产负担不均等现状并对形成总不均等的要素及子群来源进行了分解。研究表明：(1)与城乡区域因素相比，生产负担不均等更易受性别因素的影响，影响力度与生产负担的具体形式密切相关；(2)女性居民承担了更沉重的总生产负担，非SNA生产为其主要负担来源，男性居民的总生产负担较轻，其主要负担来源为SNA生产；(3)无论是居民总体还是各子群体，生产负担不均等主要归因于SNA生产负担，而子群内部不均等是造成总不均等的决定力量。     

中国区域间教育平等状况的统计考察

 本文在分析区域教育不平等表现形式的基础上构建一了套测度区域教育平等的指标体系.通过对单个指标的地区差异进行分析比较,以及对区域间教育平等状况进行综合的实证分析,提出了一些针对性的建议以改善地区教育不平等情况.     

Theory and methods for partitioned Gini coefficients computed on post-stratified data

The Gini coefficient is used to measure inequality in populations. However, shifts in the population distribution may affect subgroups differently. Consequently, it can be informative to examine inequality separately for these segments. Consider an independently and identically distributed sample split based on ranking and compute the Gini coefficient for each partition. These coefficients, calculated from post-stratified data, are not functions of U-statistics. Therefore, previous theoretical and methodological results cannot be applied. In this article, the asymptotic joint distribution is derived for the partitioned coefficients and bootstrap methods for inference are developed. Finally, an application to per capita income across census tracts is examined.