The impact of internal communication on strategic and economic effects in Serbian companies

This paper presents the research results in relation to examining and defining dependences and the impact of internal communication on certain strategic and economic business effects. Serbian companies were the focus of this research. The data were collected by polling 100 managers from 100 companies. Afterwards, multivariate regression and correlation was carried out in the aim of the final determination of requested dependences. This research confirmed a strong positive relation between internal communication and strategic and economic business effects.     

The effect of sociodemographic (mis)match between interviewers and respondents on unit and item nonresponse in Belgium

Interviewer characteristics affect nonresponse and measurement errors in face-to-face surveys. Some studies have shown that mismatched sociodemographic characteristics – for example gender – affect people's behavior when interacting with an interviewer at the door and during the survey interview, resulting in more nonresponse. We investigate the effect of sociodemographic (mis)matching on nonresponse in two successive rounds of the European Social Survey in Belgium. As such, we replicate the analyses of the effect of (mis)matching gender and age on unit nonresponse on the one hand, and of gender, age and education level (mis)matching on item nonresponse on the other hand. Recurring effects of sociodemographic (mis)match are found for both unit and item nonresponse.     

Testing variance components in balanced linear growth curve models

It is well known that the testing of zero variance components is a non-standard problem since the null hypothesis is on the boundary of the parameter space. The usual asymptotic chi-square distribution of the likelihood ratio and score statistics under the null does not necessarily hold because of this null hypothesis. To circumvent this difficulty in balanced linear growth curve models, we introduce an appropriate test statistic and suggest a permutation procedure to approximate its finite-sample distribution. The proposed test alleviates the necessity of any distributional assumptions for the random effects and errors and can easily be applied for testing multiple variance components. Our simulation studies show that the proposed test has Type I error rate close to the nominal level. The power of the proposed test is also compared with the likelihood ratio test in the simulations. An application on data from an orthodontic study is presented and discussed.     

Exact and approximate distributions for linear contrasts of means and variances

A Bayesian analysis is presented for the K-group Behrens-Fisher problem. Both exact posterior distributions and approximations were developed for both a general linear contrast of the K means and the K variances, given either proper diffuse or informative conjugate priors. The contrast of variances is a unique feature of the heterogeneous variance model that enables investigators to test specific effects of experimental manipulations on variance. Finally, important-differences were observed between the heterogeneous variance model and the homogeneous model.     

Least squares estimation of varying‐coefficient hazard regression with application to breast cancer dose‐intensity data

To enhance modeling flexibility, the authors propose a nonparametric hazard regression model, for which the ordinary and weighted least squares estimation and inference procedures are studied. The proposed model does not assume any parametric specifications on the covariate effects, which is suitable for exploring the nonlinear interactions between covariates, time and some exposure variable. The authors propose the local ordinary and weighted least squares estimators for the varying‐coefficient functions and establish the corresponding asymptotic normality properties. Simulation studies are conducted to empirically examine the finite‐sample performance of the new methods, and a real data example from a recent breast cancer study is used as an illustration. The Canadian Journal of Statistics 37: 659–674; 2009 © 2009 Statistical Society of Canada     

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。     

Abundance estimation with a categorical covariate subject to missing in continuous-time capture-recapture studies

Abstract

In continuous-time capture-recapture experiments, individual heterogeneity has a large effect on the capture probability. To account for the heterogeneity, we consider an individual covariate, which is categorical and subject to missing. In this article, we develop a general model to summarize three kinds of missing mechanisms, and propose a maximum likelihood estimator of the abundance. A likelihood ratio confidence interval of the abundance is also proposed. We illustrate the proposed methods by simulation studies and a real data example of a bird species prinia subflava in Hong Kong.     

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.