Jackknife empirical likelihood for the error variance in linear models

Variance estimation is a fundamental yet important problem in statistical modelling. In this paper, we propose jackknife empirical likelihood (JEL) methods for the error variance in a linear regression model. We prove that the JEL ratio converges to the standard chi-squared distribution. The asymptotic chi-squared properties for the adjusted JEL and extended JEL estimators are also established. Extensive simulation studies to compare the new JEL methods with the standard method in terms of coverage probability and interval length are conducted, and the simulation results show that our proposed JEL methods perform better than the standard method. We also illustrate the proposed methods using two real data sets.     

Who should care for our kids? The effects of infant child care on early child development

This paper examines the relationship between various types of child care during the first year of a child's life and the child's language and social development measured at age three. A unique contribution of the paper is the estimation of a general selection-correction model that accounts for non-random selection of children into different types of child care. The analysis uses data from the Fragile Families and Child Wellbeing Study (FFCWS), a birth cohort of children born to predominantly low-income single mothers. The results indicate that compared with maternal care, relative care during infancy has more beneficial effects on a child's language development, while day care centers have more beneficial effects on a child's behavioral development.     

The Mode of Democracy with Chinese Characteristics——Based on the Mistake-tolerant Democracy

在新的历史发展时期,民主被提升到党的生命、社会主义生命和中华人民共和国生命的历史高度。但由于我国民主理论处于发展阶段,对新出现的法制改革比如深圳市、重庆市出台的试错条例尚缺乏解释力。有鉴于此,本文基于西方学者和中国传统儒家的错误观,提出了容错性民主新概念,并在批判西方民主理论的基础上,为深圳市、重庆市试错条例的出台提供理论依据。     

新兴技术类企业竞争优势的建立:基于认知框架视角的单案例研究

新兴技术类企业通常面临来自技术端和市场端的双重约束,探究如何建立竞争优势对企业成长意义重大。以认知框架和战略转型为理论视角,通过对北京得意音通技术有限责任公司的纵向单案例研究,考察了新兴技术类企业在不同发展阶段面临的约束,分析了认知框架和战略转型的互动作用,解析了竞争优势建立的内在机理。研究结果表明:首先,新兴技术类企业在发展过程中面临技术承诺惰性,导致企业逐渐失去技术先进性带来的先发优势;其次,战略转型能有效降低新兴技术类企业的技术承诺惰性,而竞争式建构能使企业重新获得市场竞争优势;最后,新兴技术类企业从技术端向市场端转移的过程中会面临合法性约束,企业采用聚焦式建构方式,创造了市场,提高了声誉,培育了企业核心竞争力。因此,新兴技术类企业应该更加关注技术与市场的整合,通过为用户提供技术解决方案和产品来提升市场份额;企业管理者应同时关注并获取技术端和市场端的信息,培育新兴技术类企业的竞争优势。     

宏观认识新探

宏观认识是以往认识论研究关注不多的领域,但对社会认识和决策有重大影响。宏观认识的对象不能靠逻辑分析完全加以把握,需要运用直觉与逻辑相结合的方法加以处理。在宏观认识过程中,视域的自觉扩展、意义的发掘和评价、认识路径的选择和调整起着关键作用。宏观认识规律的研究需要充分利用东西方文化的思想资源,开展跨文化的合作。     

试论“迅雷不及掩耳”的演变

俗语“迅雷不及掩耳”在历史上还有其他多种变化形式,其中“疾雷不及掩耳”最常见,后者主要用于史书中的战争描写,而前者的使用更为广泛。这一俗语在漫长的演变过程中,大致出现了句式变化和字词替换两类演变方式,但主要是字词替换。通过对其各种变化形式的比较可知,记忆规律和认知心理决定了该俗语以六字为基本模式,而意义的常用性和单一性是“迅雷不及掩耳”成为最终形式的根本原因。     

The effect of Monte Carlo approximation on coverage error of double-bootstrap confidence intervals

A double-bootstrap confidence interval must usually be approximated by a Monte Carlo simulation, consisting of two nested levels of bootstrap sampling. We provide an analysis of the coverage accuracy of the interval which takes account of both the inherent bootstrap and Monte Carlo errors. The analysis shows that, by a suitable choice of the number of resamples drawn at the inner level of bootstrap sampling, we can reduce the order of coverage error. We consider also the effects of performing a finite Monte Carlo simulation on the mean length and variability of length of two-sided intervals. An adaptive procedure is presented for the choice of the number of inner level resamples. The effectiveness of the procedure is illustrated through a small simulation study.     

Minimax designs for approximately linear models with AR(1) errors

We obtain designs for linear regression models under two main departures from the classical assumptions: (1) the response is taken to be only approximately linear, and (2) the errors are not assumed to be independent, but to instead follow a first-order autoregressive process. These designs have the property that they minimize (a modification of) the maximum integrated mean squared error of the estimated response, with the maximum taken over a class of departures from strict linearity and over all autoregression parameters ρ,|ρ,| < 1, of fixed sign. Specific methods of implementation are discussed. We find that an asymptotically optimal procedure for AR(1) models consists of choosing points from that design measure which is optimal for uncorrelated errors, and then implementing them in an appropriate order.     

The relationship between crime, punishment and economic conditions: is reliable inference possible when crimes are under-recorded?

We investigate the estimation of dynamic models of criminal activity, when there is significant under-recording of crime. We give a theoretical analysis and use simulation techniques to investigate the resulting biases in conventional regression estimates. We find the biases to be of little practical significance. We develop and apply a new simulated maximum likelihood procedure that estimates simultaneously the measurement error and crime processes, using extraneous survey data. This also confirms that measurement error biases are small. Our estimation results for data from England and Wales imply a significant response of crime to both the economic and the enforcement environment.     

圆光栅刻划误差的自动校正

指出了提高圆光栅刻划精度的途径，并给出刻划误差自动校正的方法．通过对误差源的分析，找出主要误差的变化规律并导出其数学表达式，利用微机控制的专门装置，使光栅在刻划时转动一个附加角度，从而自动校正刻划误差