电商平台“砍单”行为的法律规制

在电商平台购物中发生危害消费者的公平交易权、自主选择权的经营者“砍单”行为日益增多,当事双方冲突不断。造成“砍单”行为与日俱增的根本原因是要约邀请、要约、承诺判断标准的不统一以及经营者滥用格式条款。因此,有必要对“砍单”行为进行法律规制。首先,应当注重事前规范,即统一要约邀请、要约、承诺的判断标准。其次,要规范电商经营者使用格式条款,即认定违反法律强制性规定的格式条款无效及有争议的格式条款不能单独由电商平台制定。最后,在“砍单”行为发生后,既要规范经营者对消费者的合同责任承担也要规范电商平台与经营者的责任承担,从而维护消费者的合法权益。     

Estimation of critical points in the mixture inverse Gaussian model

The maximum likelihood estimation for the critical points of the failure rate and the mean residual life function are presented in the case of mixture inverse Gaussian model. Several important data sets are analyzed from this point of view. For each of the data sets, Bootstrapping is used to construct confidence intervals of the critical points.     

全球价值链视角下中国钢铁产能过剩形成机制

国际分工背景下,提升产业价值链地位,破解低端锁定困境,既是化解过剩产能的出发点,也是落脚点。从国内制造业价值链、产业全球价值链及贸易结构等宏观层面,探究中国钢铁产业价值链低端锁定下的产能过剩形成机制,并聚焦于国际大型钢企,挖掘其微观原因。研究表明:钢铁产业处于中国制造业价值链近乎底部的位置,虽然增值能力总体有所增强,产业链条不断延伸,但与发达国家相比仍存在较大差距;在制造业价值链与钢铁产业全球价值链中存在的“微笑曲线”表明,中国钢铁产业的利润空间受到了国内外的双重挤压,产业升级压力巨大;国内议价、盈利能力普遍较差,下游业务联动不足及竞争优势缺乏是导致国内大型钢企的价值链低端锁定主要原因。目前而言,钢铁产业产能过剩与价值链低端锁定相互强化趋势明显。     

Why do participants in voluntary organizations leave? Exploring the relationship between value congruence and length of stay

Recognizing the importance of values and the specific characteristics of participants and situations in voluntary organizations, we examine how value congruence—the fit or compatibility of values between participants and the organization, or among participants—interacts with personal and situational factors to predict participants' length of stay in their organizations. Introducing the case of a voluntary organization that offers shared housing, we measure value congruence through textual similarity in the self‐introduction documents of 49 participants and the organization's mission statement. This approach differs from the self‐reported measures based on participants' perceptions or recalled interactions used in previous studies. In line with expectation‐disconfirmation theory, participants with the strongest beliefs in organizational values had shorter lengths of stay. The amount of intraorganizational communication also moderated the relationship between value congruence and length of stay. This study provides theoretical and methodological implications for nonprofit management by considering personal and situational factors and evaluating value congruence by textual similarity.     

A bootstrap control chart for inverse Gaussian percentiles

The conventional Shewhart-type control chart is developed essentially on the central limit theorem. Thus, the Shewhart-type control chart performs particularly well when the observed process data come from a near-normal distribution. On the other hand, when the underlying distribution is unknown or non-normal, the sampling distribution of a parameter estimator may not be available theoretically. In this case, the Shewhart-type charts are not available. Thus, in this paper, we propose a parametric bootstrap control chart for monitoring percentiles when process measurements have an inverse Gaussian distribution. Through extensive Monte Carlo simulations, we investigate the behaviour and performance of the proposed bootstrap percentile charts. The average run lengths of the proposed percentage charts are investigated.     

An EWMA chart for monitoring process mean

In the statistical process control literature, there exists several improved quality control charts based on cost-effective sampling schemes, including the ranked set sampling (RSS) and median RSS (MRSS). A generalized cost-effective RSS scheme has been recently introduced for efficiently estimating the population mean, namely varied L RSS (VLRSS). In this article, we propose a new exponentially weighted moving average (EWMA) control chart for monitoring the process mean using VLRSS, named the EWMA-VLRSS chart, under both perfect and imperfect rankings. The EWMA-VLRSS chart encompasses the existing EWMA charts based on RSS and MRSS (named the EWMA-RSS and EWMA-MRSS charts). We use extensive Monte Carlo simulations to compute the run length characteristics of the EWMA-VLRSS chart. The proposed chart is then compared with the existing EWMA charts. It is found that, with either perfect or imperfect rankings, the EWMA-VLRSS chart is more sensitive than the EWMA-RSS and EWMA-MRSS charts in detecting small to large shifts in the process mean. A real dataset is also used to explain the working of the EWMA-VLRSS chart.     

Transition probabilities and ARL performance of Six Sigma zone control charts

In this article, Six Sigma zone control charts (SSZCCs) are proposed for world class organizations. The transition probabilities are obtained using the Markov chain approach. The Average Run Length (ARL) values are then presented. The ARL performance of the proposed SSZCCs and the standard Six Sigma control chart (SSCC) without zones or run rules is studied. The ARL performance of these charts is then compared with those of the other standard zone control charts (ZCCs), the modified ZCC and the traditional Shewhart control chart (SCC) with common run rules. As expected, it is shown that the proposed SSZCC outperforms the standard SSCC without zones or run rules for process shifts of any magnitude. When compared to the other standard ZCCs and the Shewhart chart with common run rules, it is observed that the proposed SSZCCs have much higher false alarm rates for smaller shifts and hence they prevent unwanted process disturbances. The application of the proposed SSZCC is illustrated using a real time example.     

Multiple imputation for missing edge data: A predictive evaluation method with application to Add Health

Recent developments have made model-based imputation of network data feasible in principle, but the extant literature provides few practical examples of its use. In this paper, we consider 14 schools from the widely used In-School Survey of Add Health (Harris et al., 2009), applying an ERGM-based estimation and simulation approach to impute the network missing data for each school. Add Health's complex study design leads to multiple types of missingness, and we introduce practical techniques for handing each. We also develop a cross-validation based method – Held-Out Predictive Evaluation (HOPE) – for assessing this approach. Our results suggest that ERGM-based imputation of edge variables is a viable approach to the analysis of complex studies such as Add Health, provided that care is used in understanding and accounting for the study design.     

A comparative study of confidence intervals for negative binomial proportion

In this paper, we investigate four existing and three new confidence interval estimators for the negative binomial proportion (i.e., proportion under inverse/negative binomial sampling). An extensive and systematic comparative study among these confidence interval estimators through Monte Carlo simulations is presented. The performance of these confidence intervals are evaluated in terms of their coverage probabilities and expected interval widths. Our simulation studies suggest that the confidence interval estimator based on saddlepoint approximation is more appealing for large coverage levels (e.g., nominal level≤1% ) whereas the score confidence interval estimator is more desirable for those commonly used coverage levels (e.g., nominal level>1% ). We illustrate these confidence interval construction methods with a real data set from a maternal congenital heart disease study.     

韩国学生中介语各句长句子状语复杂度发展研究

通过分析韩国学生中介语句长为6-20个词句子的状语复杂度的发展情况,发现:初、中、高三级中介语各句长句子带状语句子比例、多层状语比例呈逐级上升趋势,多处状语比例和句首状语比例则呈逐级下降趋势;韩国学生中介语表现出句首状语比例超量、多处状语比例突出、多层状语比例不足的特点,在句长一定的前提下,多处状语与多层状语之间可能存在此消彼长的对立互补关系;研究同样发现中介语状语复杂度的发展具有不受教学输入语言制约的特点.