Estimation of geodesic tortuosity and constrictivity in stationary random closed sets

We investigate the problem of estimating geodesic tortuosity and constrictivity as two structural characteristics of stationary random closed sets. They are of central importance for the analysis of effective transport properties in porous or composite materials. Loosely speaking, geodesic tortuosity measures the windedness of paths, whereas the notion of constrictivity captures the appearance of bottlenecks resulting from narrow passages within a given materials phase. We first provide mathematically precise definitions of these quantities and introduce appropriate estimators. Then, we show strong consistency of these estimators for unboundedly growing sampling windows. In order to apply our estimators to real data sets, the extent of edge effects needs to be controlled. This is illustrated using a model for a multiphase material that is incorporated in solid oxide fuel cells.     

Testing the gender similarities hypothesis: differences in subjective task value and motivation to transfer training

ABSTRACT

Are female and male trainees similar or different in their reaction to training programmes, specifically regarding their subjective task value and motivation to transfer? According to the gender similarities hypothesis, women and men are alike on most psychological variables. However, according to research in organizational behaviour, female and male employees differ on certain aspects, such as their job satisfaction and work identity. To test these two views on gender similarities and differences in the context of human resource development and training evaluation, the present study examined the extent to which gender moderated reactions to training. Based on the expectancy-value theory of motivation and self-determination theory, a web-based questionnaire was used to measure six training reactions: intrinsic value, attainment value, utility value, perceived relative cost, autonomous motivation to transfer, and controlled motivation to transfer. The results indicated that women and men differed in their ratings of attainment value but were similar for the remaining five reaction measures. These outcomes support the gender similarities hypothesis. The findings are discussed in terms of their theoretical implications for modelling gender effects in HRD research and their practical significance for promoting training effectiveness and transfer of training.     

基于模糊TOPSIS的企业知识转移能力评价

知识转移能力作为企业获取知识、吸收知识和应用知识能力的衡量标准,是企业从事创新活动的前提和基础。以知识转移主体和客体两个要素为依据,构建企业知识转移能力指标体系,运用模糊TOPSIS法对企业知识转移能力进行综合评价,并进行实证分析,为企业制定发展战略和提高自身竞争力提供借鉴。     

基于股价预测的泛证券投资组合策略

本文基于期望效用最大化和L₁-中位数估计研究了在线投资组合选择问题。与EG（Exponential Gradient）策略仅利用单期价格信息估计价格趋势不同，本文将利用多期价格信息估计价格趋势，以提高在线策略的性能。首先，基于多期价格数据，利用L₁-中位数估计得到预期价格趋势。然后，通过期望效用最大化，提出一个新的具有线型时间复杂度的在线策略，EGLM（Exponential Gradient via L₁-Median）。并通过相对熵函数定义资产权重向量的距离，进而证明了EGLM策略具有泛证券投资组合性质。最后，利用国内外6个证券市场的历史数据进行实证分析，结果表明相较于UP（Universal Portfolio）策略和EG策略，EGLM策略有更好的竞争性能。     

政策边缘人：理解基层政策执行难的一个视角——以精准扶贫中的“争贫”为例

当公共政策只针对部分社会群体的时候，靠近政策分界线但又没有享受到政策利益的群体就会成为政策边缘人，政策边缘人属于利益外群体，但其结构性位置却又让其最接近分享政策利益，属于潜在受益者。在社会分化和竞争的背景下，政策边缘人与其他条件差不多的群体对比会产生相对剥夺感。政策边缘人会认为享有政策利益本应是他们的权利，于是他们基于维权的想法会通过各种方式谋取政策利益，在此过程中就会影响到基层公共政策的执行。因此，建议通过提高基层治理的法治化、科学化、精细化水平和组织化程度等方式减少政策边缘人对政策执行和基层治理带来的消极影响。     

Estimating the population proportion in modified ranked set sampling methods

In this paper, proportion estimators and associated variance estimators are proposed for a binary variable with a concomitant variable based on modified ranked set sampling methods, which are extreme ranked set sampling (ERSS), median ranked set sampling (MRSS), percentile ranked set sampling (Per-RSS) and L ranked set sampling (LRSS) methods. The Monte Carlo simulation study is performed to compare the performance of the estimators based on bias, mean squared error, and relative efficiency for different levels of correlation coefficient, set and cycle sizes under normal and log-normal distributions. Moreover, the study is supported with real data application.     

Optional randomized response techniques for quantitative characteristics

Gupta et al. and Huang considered optional randomized response techniques where the probability of choosing the randomized (or direct) response is fixed for all the respondents. In this paper the assumption of the constant probability of choosing the option has been relaxed by dividing respondents into two groups: one group provides direct response and the second a randomized response. The method of estimation of the population mean and variances under the modified assumption are obtained. Relative efficiencies of the proposed techniques are compared theoretically and empirically.     

Estimating ordered quantiles of two exponential populations with a common minimum guarantee time

The problem of estimating ordered quantiles of two exponential populations is considered, assuming equality of location parameters (minimum guarantee times), using the quadratic loss function. Under order restrictions, we propose new estimators which are the isotonized version of the MLEs, call it, restricted MLE. A sufficient condition for improving equivariant estimators is derived under order restrictions on the quantiles. Consequently, estimators improving upon the old estimators have been derived. A detailed numerical study has been done to evaluate the performance of proposed estimators using the Monte-Carlo simulation method and recommendations have been made for the use of the estimators.     

The relationship between ethnicity and fertility in New Zealand

While there is a global shift towards smaller families, some groups maintain relatively high fertility rates. The 2013 New Zealand census data were used to investigate the nature of fertility between ethnicities in New Zealand. The NZ Deprivation Index 2013 was used as a measure of socioeconomic status to determine the relationships with fertility. The results mirror research outside of New Zealand in that socioeconomic status is inversely correlated to fertility. Using crude average fertility rates, sole-ethnicity Pasifika and Māori ethnic groups still have substantially higher fertility than sole-ethnicity Europeans and Asians ethnic groups, even when simultaneously accounting for age, socioeconomic status, education, and religious affiliation. Christians have more children than individuals reportedly without any religion, and fertility rates drop on average for mothers who have higher formal qualifications. Our findings suggest that cultural, or other ethnic-specific factors differentially affect fertility for Māori, Pasifika, New Zealand European, and Asians as aggregated ethnic categories, respectively.     

Estimation of Mode Using Two-phase Sampling

In this article, we consider the problem of estimation of mode using two-phase sampling. Ratio- and difference-type estimators in two-phase sampling are proposed. The asymptotic properties of the proposed estimators are studied analytically as well as empirically for different situations for the given cost of surveys. The use of two-phase sampling has been found to be cost saving design while estimating mode by making a proper use of auxiliary information.