中国城乡二元结构：从“剥削型”到“保护型”

在中国,城乡二元结构不仅是一种自然的产业结构差异,更是一种国家主导的制度设置。在新中国成立后的前30年,城乡二元结构因为存在明显的“城市偏向”和对农村的政策歧视而具有某种意义上的“剥削性”。1990年代末期以来,随着市场经济的发展、人口流动的加剧以及国家惠农政策的推行,中国城乡二元结构的“剥削性”不断弱化,而“保护性”的功能则不断增强。维持“保护型”的城乡二元结构,使广大农民在市场经济中“进可攻退可守”,不仅对农民的利益保障意义重大,而且有利于维护社会结构的弹性,对农村的社会稳定和国家的经济发展具有战略性的价值。从这个意义讲,国家推行新型城镇化建设,其目标不应是以激进的方式打破城乡二元结构甚至消灭农村,而应是进一步削弱城乡二元结构的“剥削性”,强化其对农民的保护功能。     

中国制造业进口质量对出口质量的影响——基于RCEP小环流和全球大环流价值链视角

近年来,全球分工格局逐渐转变为以中国为重要枢纽的双环流格局,为中国制造业高质量进出口带来了新机遇。利用1996—2019年中国制造业进出口质量数据,考察了不同环流中中国制造业进口质量对出口质量的影响。研究发现:在RCEP小环流中,中国制造业全部产品、零部件及中间品进口质量提高均可以显著提升其出口质量以及区域价值链地位,但最终品进口质量对出口质量的影响不显著,因而中间产品进口质量的提高是推动中国制造业在该区域出口质量提升的主要因素;在全球大环流中,中国制造业进口质量提高对出口质量的提升作用相对微弱,但在RCEP小环流中进口质量的提高也可以提升其在全球大环流中的出口质量。因此,中国需加强与RCEP其他成员国的产业链分工合作,增加高质量中间产品进口,并借助在RCEP小环流中得到的提升作用,实现制造业在双环流中的高质量出口。     

Combining the complete-data and nonresponse models for drawing imputations under MAR

In multiple imputation (MI), the resulting estimates are consistent if the imputation model is correct. To specify the imputation model, it is recommended to combine two sets of variables: those that are related to the incomplete variable and those that are related to the missingness mechanism. Several possibilities exist, but it is not clear how they perform in practice. The method that simply groups all variables together into the imputation model and four other methods that are based on the propensity scores are presented. Two of them are new and have not been used in the context of MI. The performance of the methods is investigated by a simulation study under different missing at random mechanisms for different types of variables. We conclude that all methods, except for one method based on the propensity scores, perform well. It turns out that as long as the relevant variables are taken into the imputation model, the form of the imputation model has only a minor effect in the quality of the imputations.     

A dual problem of calibration of design weights

In this note, a dual problem to the calibration of design weights of the Deville and Särndal [Calibration estimators in survey sampling, J. Amer. Statist. Assoc. 87 (1992), pp. 376–382] method has been considered. We conclude that the chi-squared distance between the design weights and the calibrated weights equals the square of the standardized Z-score obtained by the difference between the known population total of the auxiliary variable and its corresponding Horvitz and Thompson [A generalization of sampling without replacement from a finite universe, J. Amer. Statist. Assoc. 47 (1952), pp. 663–685] estimator divided by the sample standard deviation of the auxiliary variable to obtain the linear regression estimator in survey sampling.     

毛泽东时代中国城镇化进程的特征分析

中国工业化的特殊道路决定了毛泽东时代中国城镇化进程的特点。这些特点不仅体现在毛泽东时代的中国城镇化进程中,而且其影响延续至今。对毛泽东时代中国城镇化的发展成就不应低估。毛泽东时代的城镇化进程奠定了改革开放后中国城镇化大发展的基础,其经历的曲折绝非毫无价值。     

基于消费者满意的双渠道销售商退款保证策略研究

研究了双渠道销售商的退款保证策略选择问题。将销售商的退款保证策略分为两个渠道都不提供、仅实体渠道提供、仅网络渠道提供以及两个渠道同时提供等四种。分别求解得到相应的最优定价及利润。研究发现:销售商在实体渠道和网络渠道的产品价格仅与其是否在该渠道提供退款保证服务有关,而与另一渠道是否提供退款保证无关。如果销售商想要刺激某渠道的利润水平,当退货产品残值较高时应选择在该渠道提供退款保证,而当残值较低时应选择在另一渠道提供退款保证。通过数值分析发现,同时在两个渠道提供退款保证并非总是销售商的最优策略。销售商的退款保证策略选择与两个渠道间的成本差异有关,当两个渠道间的成本差异较高时,销售商最好仅在网络渠道提供退款保证。     

物我对立与天人合一--论东西方文化对自然的不同认知方式产生的绘画影响

西方思想以物我对立、主客体对立的方式去看待自然,自然是人通过理性去认识和实践的对象;中国哲学主张"天人合一",人以想象和感悟来体验自然.这两种不同的认知自然的方式对于各自的风景绘画都产生了较大的影响,他们无论在绘画题材、表现手法、艺术风格、创作过程还是作品欣赏上都呈现出较大的差异.     

Tests for the umbrella alternative under normality

Consider a one-way layout of the analysis of variance assuming independence, normality, and homogeneity of variance. Test the null hypothesis H_o that the means, j., of each of Amp; columns, i = 1,…, k are equal versus the alternative that they follow an umbrella pattern. That is, the alternative is H₁-H₀ where H₁: μ₁> μ₂>… > μk, and m is known. We derive a class of tests which are unbiased and lie in a nontrivial complete class. We recommend specific tests within the class. A simulation of the power functions of some tests is contrasted with the simulated power function of the likelihood ratio test.     

Probabilistic Properties of Parametric Dual and Inverse Time Series Models Generated by ARMA Models

For the class of autoregressive-moving average (ARMA) processes, we examine the relationship between the dual and the inverse processes. It is demonstrated that the inverse process generated by a causal and invertible ARMA (p, q) process is a causal and invertible ARMA (q, p) model. Moreover, it is established that this representation is strong if and only if the generating process is Gaussian. More precisely, it is derived that the linear innovation process of the inverse process is an all-pass model. Some examples and applications to time reversibility are given to illustrate the obtained results.     

Obtaining least absolute value estimates for a two-way classification model

The importance of the two-way classification model is well known, but the standard method of analysis is least squares. Often, the data of the model calls for a more robust estimation technique. This paper demonstrates the equivalence between the problem of obtaining least absolute value estimates for the two-way classification model and a capacitated transportation problem. A special purpose primal algorithm is developed to provide the least absolute value estimates. A computational comparison is made between an implementation of this specialized algorithm and a standard capacitated transportation code.