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本文通过实验比较了互信息、χ2统计算法和优势率三种算法在用于局部文本特征选取时对文本分类性能的影响.实验结果显示,在应用于局部特征选择的情况下,文本特征选取算法仍然可以将特征空间的维度降低90%以上,而不降低文本分类的性能.同时,我们发现在应用于局部文本特征选取时,优势率算法的性能不如互信息和χ2统计算法.另外,对于K最近邻分类算法,随着K值的增大,文本分类的查准率在增加,而查全率在降低.最后,本文详细分析了造成这三种算法性能差异的原因,并提出了一种改进算法,来提高优势率算法应用于局部文本特征选取时的性能. 相似文献
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谈网球正拍和反拍击球技术教学 总被引：1，自引：0，他引：1
林辉杰 《吉林体育学院学报》2005,21(2):111-112
对网球正拍和反拍击球技术的环节和各环节的要领进行了新探和理顺，从教学实践出发，探讨了它们的教学流程、教学关键点以及学生易犯错误和纠正方法等内容，旨在交流网球教学经验和指导网球教学实践。 相似文献
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ABSTRACTThe present study aims to investigate the ability of a new framework enabling to derive more detailed model-based predictions from ranking systems. These were compared to predictions from the bet market including data from the World Cups 2006, 2010, and 2014. The results revealed that the FIFA World Ranking has essentially improved its predictive qualities compared to the bet market since the mode of calculation was changed in 2006. While both predictors were useful to obtain accurate predictions in general, the world ranking was able to outperform the bet market significantly for the World Cup 2014 and when the data from the World Cups 2010 and 2014 were pooled. Our new framework can be extended in future research to more detailed prediction tasks (i.e., predicting the final scores of a match or the tournament progress of a team). 相似文献
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《Sport Management Review》2016,19(3):319-331
Gambling promotions extensively punctuate contemporary televised sport broadcasts and concerns have been raised about their potential impacts on vulnerable groups. Research suggests advertising can shape individuals’ emotions, or affect, towards a product/brand and can subsequently influence purchasing decisions. Consequently, understanding how promotion of gambling influences sport viewers is an important although sparsely addressed area of research. This paper presents exploratory research on affective responses towards gambling promotions displayed during televised sport. Eight online focus groups were conducted with a sample of regular sports viewers in Queensland, Australia. Participants were exposed to a variety of gambling promotions used in National Rugby League match telecasts. Utilising adaptive theory, themes reflecting affective responses to each promotional technique were identified. A range of positive and negative affective responses were identified including arousal, joy, anger and worry. A conceptual model representing emergent affective response categories, message delivery techniques and moderating variables is proposed to inform a broader future research agenda examining how gambling promotions during televised sport influence affective response and concomitant gambling intention. 相似文献
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网络体育赌博是指人们拿足球、篮球等比赛结果、球员以及相关的事实通过网络进行赌博的行为。网络赌博是一种新的形式,更加具有隐蔽性。2014年巴西世界杯期间,网络体育赌博俨然成为中国的全民话题。运用文献资料、案例分析等研究方法,对网络体育赌博问题进行了初步的研究,对网络体育赌博快速增长的社会背景和致因分析,并对网络体育赌博问题的遏制策略提出了建议和观点。 相似文献
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The sign of an association measure between two varibles may be strongly affected and even be reversed after marginalization over a backgruoud variable, which is the well-known Yule-Simpson paradox.Odds ratios are strongly collapsible over a background variable if they remain unchanged no matter how the background variable is partially pooled.In this paper, we firstly give some definitions and notations about odds ratios between a dichotomous explanatory variable and a continuous response variable.Then, we present conditions for simple collapsibility of odds ratios.Further, necessary and sufficient conditions are given for strong collapsibility of odds ratios for continuous outcome variable. 相似文献
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Mike Huggins 《国际体育史杂志》2013,30(5):667-683
The catastrophe of the Second World War had a significant effect on British social and economic life, with less leisure and more time and energy spent on the war effort, yet sports betting survived. The paper begins by examining the arguments strongly advanced by vociferous anti-betting groups in the first years after the outbreak of war, and assesses their limited success. Assessments of betting turnover suggest an initial decline in betting, largely perhaps because of the brief curtailment of horse racing, dog racing, and football, the three principal betting media. The paper explores some of the reasons why it then once more increased, according to the surveys of the Churches Committee on Gambling or Mass Observation. The argument focuses on provision and betting organization: the continued legal opportunities within Britain, including new ‘unity’ football pools, the reopening of some English racecourses and dog-tracks, and the new opportunities created by illegal ready-money bookmakers, such as Irish horse-racing results, which were unaffected by the war. The national government took the view that the betting sports were ‘entertainments’ and ‘in the public interest’, and also helped by providing scarce petrol to assist with the movement of horses and dogs to meetings. 相似文献
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Mike Huggins 《国际体育史杂志》2013,30(11):1529-1552
Historiography has largely focused on more respectable Anglo-Jewish leisure life in the nineteenth and early twentieth centuries, but this study uses the national and regional press, contemporary novels, books and magazines to explore non-Jewish representations of Jewish sports betting and related gambling involvement, and the extent to which such representations involved anti-Semitic attitudes. In part Jewish betting and gambling simply attracted similar respectable opprobrium to that of working-class gambling more generally, and prejudice was not a consistent feature. But at times, coverage suggested that Jews were greedier for money, less honest and more attracted to betting than other ethnic groups. Where Jews were involved in criminal activities, such as racecourse frauds in the 1840s, gaming room presence throughout the period, or the involvement of bookmakers in racecourse feuding in the inter-war period, such activities were sometimes deliberately foregrounded. Some rich Jews became involved in racehorse ownership, but with the exception of the Rothschild family they were excluded from Jockey Club membership. In the interwar period, the British Union of Fascists exploited any Jewish involvement in betting as part of their anti-Semitic propaganda. 相似文献
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Maternal mental disorders are known risk factors for child mistreatment. However, little is known about the involvement of maternal developmental disorder traits. The aim of this study was to examine maternal traits related to Pervasive Developmental Disorder (PDD) and Attention Deficit Hyperactivity Disorder (ADHD), and their possible association with child mistreatment. Maternal PDD and ADHD were assessed through a self-administered questionnaire (N = 846) during mid-pregnancy using the Pervasive Developmental Disorders Autism Society Japan Rating Scale (PARS) and Adult ADHD Self-Report Scale (ASRS). The mothers completed another questionnaire on child mistreatment when the offspring was approximately 18 months of age. The associations between maternal PDD and ADHD traits and child mistreatment score were analyzed using linear regression models adjusted for covariates. Mothers who exhibited stronger PDD traits showed significantly higher child mistreatment score, even after adjustment for maternal characteristics at baseline and ADHD traits. At the same time, ADHD traits were significantly associated with child mistreatment after adjustment of covariates, although the association became non-significant after adjustment of PDD traits. Mothers who showed PDD and ADHD traits during pregnancy were more likely to mistreat their children. It is essential to educate mothers with such traits with appropriate, easy-to-follow childcare instructions, preferably in simple language combined with pictorial aids. 相似文献