资本回报率、人力资本投资与收入不平等——基于Galor-Zeira模型的扩展

资本回报率下降对人力资本投资、收入不平等程度有较大影响。本文将可变资本回报率加入Galor-Zeira模型,理论推导发现:收入不平等陷阱并非不可逾越的障碍。当技能劳动力工资高于受教育固定成本时,随着资本回报率下降,接受教育的遗赠临界水平将降低,更多家庭将发现投资人力资本是有利的,稳态的技能劳动力比例将提高。在当前资本回报率下降的大背景下,提高技能劳动力工资、降低受教育成本、对教育贷款实施财政减免优惠、为农村中等教育支出减负和提升农村教育质量、倡导节俭和重视遗赠的文化氛围在长期都有助于提高技能劳动力比重以及缓和收入不平等。     

Consistent inference in fixed-effects stochastic frontier models

The classical stochastic frontier panel data models provide no mechanism to disentangle individual time invariant unobserved heterogeneity from inefficiency. Greene (2005a, b) proposed the so-called “true” fixed-effects specification that distinguishes these two latent components. However, due to the incidental parameters problem, his maximum likelihood estimator may lead to biased variance estimates. We propose two alternative estimators that achieve consistency for $n\to \infty$ with fixed $T$. Furthermore, we extend the Chen et al. (2014) results providing a feasible estimator when the inefficiency is heteroskedastic and follows a first-order autoregressive process. We investigate the behavior of the proposed estimators through Monte Carlo simulations showing good finite sample properties, especially in small samples. An application to hospitals’ technical efficiency illustrates the usefulness of the new approach.     

Density estimation in the uniform deconvolution model

We consider the problem of estimating a probability density function based on data that are corrupted by noise from a uniform distribution. The (nonparametric) maximum likelihood estimator for the corresponding distribution function is well defined. For the density function this is not the case. We study two nonparametric estimators for this density. The first is a type of kernel density estimate based on the empirical distribution function of the observable data. The second is a kernel density estimate based on the MLE of the distribution function of the unobservable (uncorrupted) data.     

精馏过程的节能和优化设计的探讨

精馏过程的节能,对于减少能源消耗,降低生产成本和保护环境具有十分重要的意义.在精馏过程中可以采用最适宜回流比操作和最佳进料状态,使用中间冷凝器和中间再沸器,高效精馏、热泵精馏.合理安排多组分物料分离流程,直接利用过程热量及开发应用高效换热器等措施.本文从最佳回流比R的选择、进料温度及进料状态的确定等方面,详细的分析了在精馏塔的设计过程中,如何实现设计的优化问题,以实现节能降耗.     

对小地区失业统计差额比的推定

本文对韩国国内行政区域如市郡区等小地区的失业统计共同差额比进行推定的方法有联合推定量,Woolf推定量和Mantel-Haenszel推定量等。对这个推定量的可信度是通过偏差和平均平方误差的概念来进行比较的。从对京畿地区经济活动人口调查情况看,这个地区内的24个市郡单位行政自治地区的男、女失业率差额比的偏差及平均平方误差是通过本次研究提出的推定程序来推定的。这些推定数的稳定性和效率性可以通过相对偏差和相对平均误差平方根来评价。Woolf推定量或Mantel-Haenszel推定量比联合推定量更为稳定,从其效率性来看三者很相似。     

中国税收流失规模估测

无论地下经济还是公开经济都存在税收流失问题.本文采用一定的方法分别对我国1982-2002年间地下经济和公开经济的税收流失规模进行了估测.从税收流失的规模角度看,我国税收的汲取能力比较弱,蕴涵着很大的税收风险.减少税收流失应作为税制改革的重要目标.     

浙江上市公司总体分析

浙江上市公司从数量上看，占了相当优势，排在全国的第4位，而且至今还未曾有退市的公司；从质量上看，也有较突出的特征，该板块的平均净资产值较高，按上市公司数量排的全国前10位中，排在第1位，达3．23元；从市盈率来看也说明了浙江板块的业绩较好，平均市盈率已达17．66倍。但也存在不足的一面，从对社会贡献的总量来看，还不是很突出，缺乏规模效益。     

FACTORS THAT AFFECT THE LONG‐TERM SURVIVAL OF MICRO,SMALL AND MEDIUM ENTERPRISES IN ETHIOPIA

There is an increasing recognition of the potential importance of micro, small and medium enterprises (MSMEs) for employment, income and poverty reduction in Ethiopia. Although the MSME sector contributes significantly to the national economy, the high failure rate among well established small businesses and enterprises is a matter of major concern. A random sample of 500 small businesses and enterprises selected from five major cities in Ethiopia were followed up for 6 years in order to assess the impact of influential factors that affect the long‐term survival and viability of small enterprises. Hazard ratios estimated from the Cox Proportional Hazards Model were used to quantify the impact of key predictors of survival. Businesses that ceased operation were characterised by inadequate finance (61%), low level of education (55%), poor managerial skills (54%), shortage of technical skills (49%), and inability to convert part of their profit to investment (46%). The study shows that participation in social capital and networking (iqqub schemes) was critically helpful for long‐term survival. Businesses that did not participate in iqqub schemes regularly were found to be 3.25 times more likely to fail in comparison with businesses that did. Results of the study have implications that could be used for developing policy initiatives that are aimed at fostering long‐term growth in small businesses and enterprises.     

上市公司利润操纵的经济动机

政府的每一次政策出台都为企业带来了新的生机与动力,但同时也诱导着一些企业进行着利润操 纵,我们应该看到,中国股票市场走过的10年道路中,规范与反规范的争斗从来没有停止过,正是由于 这样,促使我国证券市场不断发展。     

Asymptotically optimal estimation of smooth functionals for interval censoring, part 1

Estimation in the interval censoring model is considered. A class of smooth functionals is introduced, of which the mean is an example. The asymptotic information lower bound for such functionals can be represented as an inner product of two functions. In case 1, i.e. one observation time per unobservable event time, both functions can be given explicitly. We mainly consider case 2, with two observation times for each unobservable event time, in the situation that the observation times can not become arbitrarily close to each other. For case 2, one of the functions in the inner product can only be given implicitly as solution to a Fredholm integral equation. We study properties of this solution and, in a sequel to this paper, prove that the nonparametric maximum likelihood estimator of the functional asymptotically reaches the information lower bound.