城市人力资本外部性的识别——基于工业企业生产率视角的研究

人力资本外部性的存在具有重要的现实意义,它是政府进行教育投资和人力资本投资的重要决策依据.文章从工业企业生产率视角识别城市人力资本外部性,基于中国工业企业微观数据、人口普查分县资料和地级市统计数据,考虑城市人力资本变量的内生性后,采用两阶段最小二乘法,实证研究城市人力资本对工业企业生产率的影响.研究发现:在控制企业自身的人力资本后,城市大专以上学历人口占比越高,工业企业的产出越高,人力资本的溢出效应显著,且人力资本正外部性主要存在于人口规模300万以上的大城市.从工业内部看,行业内人力资本正外部性随城市规模扩大逐渐增强,而行业外人力资本正外部性随城市规模扩大逐渐减弱.从企业异质性看,高新技术企业、非国有企业和大企业从城市人力资本提高中获得的正向溢出效应更大.此外,城市外商直接投资和地方政府财政支出越高,地理区位距离港口越远,越不利于工业企业产出的提高.文章的研究结论表明增加人力资本投资,促进人力资本结构升级,发挥大城市人力资本溢出效应对新时期经济可持续增长尤为重要.     

Bootstrapping mean‐squared errors of robust small‐area estimators: Application to the method‐of‐payments surveys data

This paper proposes a new bootstrap procedure for mean‐squared errors of robust small‐area estimators. We formally prove the asymptotic validity of the proposed bootstrap method and examine its finite‐sample performance through Monte Carlo simulations. The results show that our procedure performs well and competes with existing ones. We also provide an application to the estimation of the total volume and value of cash, debit card, and credit card transactions in Canada as well as in its provinces and subgroups of households. In particular, we found that there is a significant average annual decline rate of 3.1% in the volume of cash transactions and that this decline is relatively higher among high‐income households living in heavily populated provinces. Our bootstrap estimator also provides indicators of quality useful in selecting the best small‐area predictor among several alternatives in practice.     

Business structure,ethnic shifts in labor markets,and violence: The link between company size,local labor markets,and non-Latino homicide

Combining several schools of thought, including the civic engagement thesis, we extend current research by linking three things at the county level; firm size, the ethnic composition of labor markets, and violent crime. Our results suggest that larger businesses (based on the average number of persons employed) are more likely to have an external orientation and long recruitment reach, and this is linked to ethnic shifts in labor markets toward Latino workers. Such shifts are in turn associated with high rates of homicide among non-Latinos. Through indirect effects modeling, we find that increases in Black homicide are linked to rises in concentrated poverty, while increases in White homicide are linked to changes in unemployment. We discuss the implications of our findings.     

Analysis of a two incongruent arrivals and services M/G/1 queue with random feedback

A queuing system with two incongruent arrivals and services is considered. Two kinds of customers enter the system by Poisson process and the service times are assumed to have general distribution. After first kind service completion, it may feedback to repeat the first service, leave the system or go to give second service. The same policy is applied for the other kind of customer. All stochastic processes involved in this system are independent. We derive the probability generating function for each kind and for the system that yield the performance measures. Some numerical approaches examined the validity of the results.     

应用激光透射信号随机波动特性求取颗粒尺寸及浓度

阐述了利用穿越介质后的激光信号的随机波动来测量颗粒尺寸和浓度的原理和方法,并在实验室条件下对标准颗粒进行了验证,实验结果表明,该方法在低颗粒浓度和较高浓度时都能得到的测量结果,建立在该原理上的测量仪器结构简单,对环境要求低,无需特殊的保护措施,这些特点为工业生产中的在线监测提供了一种有效的方法。     

Do Political Institutions Shape Economic Policy?

Do political institutions shape economic policy? I argue that this question should naturally appeal to economists. Moreover, the answer is in the affirmative, both in theory and in practice. In particular, recent theoretical work predicts systematic effects of electoral rules and political regimes on the size and composition of government spending. Results from ongoing empirical work indicate that such effects are indeed present in the data. Some empirical results are consistent with theoretical predictions: presidential regimes have smaller governments and countries with majoritarian elections have smaller welfare‐state programs and less corruption. Other results present puzzles for future research: the adjustment to economic events appears highly institution‐dependent, as does the timing and nature of the electoral cycle.     

中国城市规模分布及影响因素实证研究

文章应用城市位序—规模法则与分形理论,测算了1999—2008年间分别以城市人口、建成区面积和经济规模表征的中国城市规模分布分维值,对分维值进行了纵向对比分析,并实证分析了影响城市规模的主要因素。研究结果显示：中国城市规模分布具有显著的分形特征,符合城市位序—规模法则;1999—2008年间三种表征的中国城市规模分布分维值均呈现下降趋势;中国城市规模具有明显区域性差异,资本投入、科技水平、产业结构和外资是推动城市规模扩大的重要因素。最后,文章据此提出了发展和完善中国城市规模体系的对策建议。     

High dimensional asymptotics for the naive Hotelling T2 statistic in pattern recognition

Abstract

This paper examines the high dimensional asymptotics of the naive Hotelling T² statistic. Naive Bayes has been utilized in high dimensional pattern recognition as a method to avoid singularities in the estimated covariance matrix. The naive Hotelling T² statistic, which is equivalent to the estimator of the naive canonical correlation, is a statistically important quantity in naive Bayes and its high dimensional behavior has been studied under several conditions. In this paper, asymptotic normality of the naive Hotelling T² statistic under a high dimension low sample size setting is developed using the central limit theorem of a martingale difference sequence.     

Adaptive designs for IVPT data with mixed scaled average bioequivalence

In vitro permeation tests (IVPT) offer accurate and cost-effective development pathways for locally acting drugs, such as topical dermatological products. For assessment of bioequivalence, the FDA draft guidance on generic acyclovir 5% cream introduces a new experimental design, namely the single-dose, multiple-replicate per treatment group design, as IVPT pivotal study design. We examine the statistical properties of its hypothesis testing method—namely the mixed scaled average bioequivalence (MSABE). Meanwhile, some adaptive design features in clinical trials can help researchers make a decision earlier with fewer subjects or boost power, saving resources, while controlling the impact on family-wise error rate. Therefore, we incorporate MSABE in an adaptive design combining the group sequential design and sample size re-estimation. Simulation studies are conducted to study the passing rates of the proposed methods—both within and outside the average bioequivalence limits. We further consider modifications to the adaptive designs applied for IVPT BE trials, such as Bonferroni's adjustment and conditional power function. Finally, a case study with real data demonstrates the advantages of such adaptive methods.