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111.
This article presents evidence that published results of scientific investigations are not a representative sample of results of all scientific studies. Research studies from 11 major journals demonstrate the existence of biases that favor studies that observe effects that, on statistical evaluation, have a low probability of erroneously rejecting the so-called null hypothesis (H 0). This practice makes the probability of erroneously rejecting H 0 different for the reader than for the investigator. It introduces two biases in the interpretation of the scientific literature: one due to multiple repetition of studies with false hypothesis, and one due to failure to publish smaller and less significant outcomes of tests of a true hypotheses. These practices distort the results of literature surveys and of meta-analyses. These results also indicate that practice leading to publication bias have not changed over a period of 30 years.  相似文献   
112.
113.
在全面修订《汉语大词典》的同时,中国还需要一部与国家形象和时代要求相适应的在线《汉语大词典》。文章在分析国内外电子辞书发展现状的基础上,就在线《汉语大词典》的基本原则、需要解决的问题等提出了建议和设想。  相似文献   
114.
The canadian traveller problem and its competitive analysis   总被引:1,自引:0,他引:1  
From the online point of view, we study the Canadian Traveller Problem (CTP), in which the traveller knows in advance the structure of the graph and the costs of all edges. However, some edges may fail and the traveller only observes that upon reaching an adjacent vertex of the blocked edge. The goal is to find the least-cost route from the source O to the destination D, more precisely, to find an adaptive strategy minimizing the competitive ratio, which compares the performance of this strategy with that of a hypothetical offline algorithm that knows the entire topology in advance. In this paper, we present two adaptive strategies—a greedy or myopic strategy and a comparison strategy combining the greedy strategy and the reposition strategy in which the traveller backtracks to the source every time when he/she sees a failed edge. We prove tight competitive ratios of 2 k+1−1 and 2k+1 respectively for the two strategies, where k is the number of failed edges in the graph. Finally, we propose an explanation of why the greedy strategy and the comparison strategy are usually preferred by drivers in an urban traffic environment, based on an argument related to the length of the second-shortest path in a grid graph. We would like to acknowledge the support from NSF of China (No. 70525004, No. 70121001 and No. 60736027), and the support from K.C. Wong Education Foundation, Hong Kong.  相似文献   
115.
We propose a monitoring procedure to test for the constancy of the correlation coefficient of a sequence of random variables. The idea of the method is that a historical sample is available and the goal is to monitor for changes in the correlation as new data become available. We introduce a detector which is based on the first hitting time of a CUSUM-type statistic over a suitably constructed threshold function. We derive the asymptotic distribution of the detector and show that the procedure detects a change with probability approaching unity as the length of the historical period increases. The method is illustrated by Monte Carlo experiments and the analysis of a real application with the log-returns of the Standard & Poor's 500 (S&P 500) and IBM stock assets.  相似文献   
116.
We propose a new regression-based filter for extracting signals online from multivariate high frequency time series. It separates relevant signals of several variables from noise and (multivariate) outliers.

Unlike parallel univariate filters, the new procedure takes into account the local covariance structure between the single time series components. It is based on high-breakdown estimates, which makes it robust against (patches of) outliers in one or several of the components as well as against outliers with respect to the multivariate covariance structure. Moreover, the trade-off problem between bias and variance for the optimal choice of the window width is approached by choosing the size of the window adaptively, depending on the current data situation.

Furthermore, we present an advanced algorithm of our filtering procedure that includes the replacement of missing observations in real time. Thus, the new procedure can be applied in online-monitoring practice. Applications to physiological time series from intensive care show the practical effect of the proposed filtering technique.  相似文献   
117.
重点关注于网络空间里族群成员如何将其族群身份进行视觉化的符号展演。在对三茁网论坛注册用户名进行数据统计和结构性访谈后发现,虚拟社区中的成员通过注册用户名、上传图片头像与添加签名档内容三个符号化方式来展演族群身份,其身份展演具有七个特征:泛族群认同、随时性、可视化/视觉化、一定的真实性、无龄感和跨性别。论坛活动的参与有助于族群成员加强其族群认同。  相似文献   
118.
网络环境中,消费者信息的搜集和利用已经逐渐成为商家经营的基本手段,而在这一过程中反映出的消费者信息被侵害的案例已屡见不鲜。从在线消费者信息被侵害的案例说开去,通过分析在线消费者信息被利用的主要形式,从法律视角探析在线消费者信息享有者和利用者的权利义务关系,从而在分析我国目前立法现状的基础上提出完善相关法律的思考和构想。  相似文献   
119.
随着新媒体的发展壮大,传统期刊的办刊模式已远远落后于时代要求,办刊质量也亟待提高。然而我们也要看到传统期刊具有影响大、出版资源丰富等优势,传统期刊为应对生存危机必须变短板为长板,打造出自身的特色;变单纯地编辑期刊为经营期刊,向市场求生存要发展;跟上时代潮流,学习新知识,勇于创新。  相似文献   
120.
Disabled people face hostility and harassment in their socio-cultural environment. The use of electronic communications creates an online context that further reshapes this discrimination. We explored the experiences of 19 disabled victims of cyberharassment. Five themes emerged from the study: disability and health consequences, family involvement, misrepresentation of self, perceived complexity, and lack of awareness and expertise. Cyberharassment incidents against disabled people were influenced by the pre-existing impairment, perceived hate-targeting, and perpetrators faking disability to get closer to victims online. Our findings highlight a growing issue requiring action and proper support.  相似文献   
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