On the existence of linear trend free block designs

We present a class of counerexamples for a conjecture on the existence or linear trend free block designs we will also prove a considerably weakened version of this conjecture which will determine all combinations of designs parmetres for which the class of linear trend free block designs is non empty.     

外商直接投资对民族地区经济的影响及对策

目前对于民族地区吸收FD I(外商直接投资),学界尚存在着许多错误看法,这些看法片面地夸大外国直接投资给民族地区带来的好处,低估甚至根本抹煞它对民族经济的负面影响。认为FD I对民族地区的经济发展只存在正面效应,因此主张越多越好。笔者认为,对于FD I对民族经济的影响应该从正、反两方面进行考察,应客观地剖析两大利益主体之间的博弈。     

中国沪深股市的开盘效应与收盘效应

股票市场的日历效应历来受到学者和投资者的广泛关注,研究发现股市存在节日效应、月份效应与周内效应,但是针对日内效应的研究不多见.利用沪深股指2004年~2016年的高频数据,实证检验中国沪深股市是否存在日内效应,结果表明:中国沪深股市整体上存在开盘效应与收盘效应,但在牛市、熊市期间的表现形式存在差异,股指收益在牛市期间表现出正向开盘效应,在熊市期间表现出负向开盘效应,股指波动在熊市期间的开盘效应更为明显.基于滚动窗口法的进一步研究发现:股指收益开盘效应和收盘效应的变化领先于股指走势的变化,股指收益和波动的开盘效应或收盘效应存在一定程度的替代现象.研究有助于投资者合理地制定投资策略,对监管部门维护市场秩序具有一定的参考价值.     

农产品网购意愿影响因素及作用机理研究——基于参照效应视角的分析

以整合型科技接受和使用模型(UTAUT)和价值接受模型(VAM)为基础,通过构建参照群体、参考价格、积极在线评论与感知价值、感知风险以及购买意愿之间的关系模型,从参照效应视角实证分析了农产品网购意愿的影响因素及作用机理,并探讨了消费者农产品质量与安全意识在参照效应影响网购意愿中的调节作用.结果表明:参照效应对农产品网购意愿有显著影响;感知价值和感知风险在参照效应影响网购意愿中均发挥了中介作用,但感知价值的中介作用显著大于感知风险;消费者农产品质量与安全意识在参照效应影响网购意愿中部分地发挥了调节效应.其中,对参照群体和积极在线评论的调节效应显著,即网购过程中,消费者越是重视农产品质量与安全,参照群体的意见和积极在线评论对其网购意愿的影响就会越凸显.     

汇改后中国外汇市场与资本市场联动效应——基于集合经验模态分解法

以投资者预期收益变动逻辑起点,构建在不同预期收益下外汇市场与资本市场的联动机制理论模型,进而将2005-2014年按金融市场改革历程划分为4个阶段,通过集合经验模态分解法对中国外汇市场与资本市场的数据进行分解,过滤掉代表资本价格随机波动的短周期分量,提取最具代表联动性的长周期趋势分量。采用VAR-GARCH-BEKK模型对4个阶段两个市场的均值溢出效应和波动溢出效应进行分析,结果显示:受中国经济增长的方式以及外汇管制制度影响,不同阶段两个市场间的溢出效应呈现出不同的特点,虽然总体来看联动强度有一定程度的加强,但是两个市场间"资金价格"传导机制的脆弱性并未获得实质性的改变。因此,只有推进汇率市场化,循序渐进的加快资本项目可兑换,完善人民币汇率形成机制,才能够不断提高货币政策调控的主动性和有效性性,维护国家利益。     

论现代汉语中的“T1+（的）+T2”结构

现代汉语中存在着这样一种特殊的复合时间结构——T1+（的）+T2,T1、T2均是具有指示性的时点。在言语交际过程中, 人们常使用“T1+（的）+T2”这类复合时间结构的语言表达式,将原来具有一定距离的“事件”（包括已然事件和未然事件）拉回 到现时,从而产生加强现场感的语用效果,且站在说话人角度,具有积极的交际效果。     

Evaluating the Use of Spatial Covariance Structures in the Analysis of Cardiovascular Imaging Data

This article investigates the choice of working covariance structures in the analysis of spatially correlated observations motivated by cardiac imaging data. Through Monte Carlo simulations, we found that the choice of covariance structure affects the efficiency of the estimator and power of the test. Choosing the popular unstructured working covariance structure results in an over-inflated Type I error possibly due to a sample size not large enough relative to the number of parameters being estimated. With regard to model fit indices, Bayesian Information Criterion outperforms Akaike Information Criterion in choosing the correct covariance structure used to generate data.     

Collective versus Individual Effects in Survival Analysis of Multiple Failures

In survival analysis, we sometimes encounter data with multiple censored outcomes. Under certain scenarios, partial or even all covariates have ‘similar’ relative risks on the multiple outcomes in the Cox regression analysis. The similarity in covariate effects can be quantified using the proportionality of regression coefficients. Identifying the proportionality structure, or equivalently whether covariates have individual or collective effects, may have important scientific implications. In addition, it can lead to a smaller set of unknown parameters, which in turn results in more accurate estimation. In this article, we develop a novel approach for identifying the proportionality structure. Simulation shows the satisfactory performance of the proposed approach and its advantage over estimation under no assumed structure. We analyse three datasets to demonstrate the practical application of the proposed approach.     

Investigating impacts of complex sampling on latent growth curve modelling

We investigate the impacts of complex sampling on point and standard error estimates in latent growth curve modelling of survey data. Methodological issues are illustrated with empirical evidence from the analysis of longitudinal data on life satisfaction trajectories using data from the British Household Panel Survey, a national representative survey in Great Britain. A multi-process second-order latent growth curve model with conditional linear growth is used to study variation in the two perceived life satisfaction latent factors considered. The benefits of accounting for the complex survey design are considered, including obtaining unbiased both point and standard error estimates, and therefore correctly specified confidence intervals and statistical tests. We conclude that, even for the rather elaborated longitudinal data models that were considered, estimation procedures are affected by variance-inflating impacts of complex sampling.     

Cultural capital or relative risk aversion? Two mechanisms for educational inequality compared1

In this paper we empirically examined two explanatory mechanisms for educational inequality: cultural reproduction and relative risk aversion, using survey data taken from secondary school pupils in Amsterdam. Cultural reproduction theory seeks to explain class variations in schooling by cultural differences between social classes. Relative risk aversion theory argues that educational inequalities can be understood by between-class variation in the necessity of pursuing education at branching points in order to avoid downward mobility. We showed that class variations in early demonstrated ability are for a substantial part cultural: cultural capital - measured by parental involvement in highbrow culture - affected school performance at the primary and secondary level. However, relative risk aversion - operationalized by being concerned with downward mobility - strongly affects schooling ambitions, whereas cultural capital had no effect. Thus, we conclude that 'primary effects' of social origin on schooling outcomes are manifested through cultural capital and not through relative risk aversion (in addition to other potential sources of class variations such as genetics). Relative risk aversion, and not cultural capital, affects schooling ambitions, which is relevant for our understanding of secondary effects.