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Measuring Search Engine Quality 总被引:12,自引:3,他引:9
The effectiveness of twenty public search engines is evaluated using TREC-inspired methods and a set of 54 queries taken from real Web search logs. The World Wide Web is taken as the test collection and a combination of crawler and text retrieval system is evaluated. The engines are compared on a range of measures derivable from binary relevance judgments of the first seven live results returned. Statistical testing reveals a significant difference between engines and high intercorrelations between measures. Surprisingly, given the dynamic nature of the Web and the time elapsed, there is also a high correlation between results of this study and a previous study by Gordon and Pathak. For nearly all engines, there is a gradual decline in precision at increasing cutoff after some initial fluctuation. Performance of the engines as a group is found to be inferior to the group of participants in the TREC-8 Large Web task, although the best engines approach the median of those systems. Shortcomings of current Web search evaluation methodology are identified and recommendations are made for future improvements. In particular, the present study and its predecessors deal with queries which are assumed to derive from a need to find a selection of documents relevant to a topic. By contrast, real Web search reflects a range of other information need types which require different judging and different measures. 相似文献
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Chris Davies 《English in Education》1991,25(3):28-31
The unity of "unitary" English, subsuming "language" and "literature", has always been a central tenet of NATE thinking and a basic assumption of most progressive practice, and is now enshrined in the National Curriculum1 . In this article, however, Chris Davies makes the scandalous proposal that the time has come when "language" and "literature", radically transformed, would be better separated. 相似文献
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长期以来,企业通常利用年龄、收入、性别与受教育程度等基本的人口统计信息来进行市场定位并制定营销战略。 相似文献
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Chris Du Feu 《Teaching Statistics》2006,28(3):66-70
Biodiversity is a difficult concept. It can be introduced to young children successfully, laying the foundations for further study in later years. This article describes one practical activity for 5‐ and 6‐year‐old children. 相似文献
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1 Introduction New technologies and other developments haye changedthe information seeking behaviors of the academic communityand the general public.Nowhere is this more evident than inthe exponential growth of the World Wide Web and cellularphone usage.Responding to these user needs and newtechnologies,libraries are moving from being InformationWarehouses to becoming Information Portals.Full-text 相似文献
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Chris Brown 《图书馆管理杂志》2018,58(4):375-381
This article proposes the incorporation of learning science into the programming and operation of public libraries. Learning science, a multidisciplinary field spanning cognitive science, psychology, neuroscience, economics, anthropology, and linguistics, has identified proven methods for enhancing learning at any age. The article highlights some of the tools and insights that are most relevant to libraries in their role as centers for informal learning. 相似文献
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Chris Bishop Lucas A. Pereira Valter P. Reis Paul Read Anthony N. Turner Irineu Loturco 《Journal of sports sciences》2020,38(11-12):1296-1303
ABSTRACT The aims of the present study were to provide an in-depth comparison of inter-limb asymmetry and determine how consistently asymmetry favours the same limb during different vertical jump tests. Eighteen elite female under-17 soccer players conducted unilateral squat jumps (SJ), countermovement jumps (CMJ) and drop jumps (DJ) on a portable force platform, with jump height, peak force, concentric impulse and peak power as common metrics across tests. For the magnitude of asymmetry, concentric impulse was significantly greater during the SJ test compared to CMJ (p = 0.019) and DJ (p = 0.003). No other significant differences in magnitude were present. For the direction of asymmetry, Kappa coefficients revealed fair to substantial levels of agreement between the SJ and CMJ (Kappa = 0.35 to 0.61) tests, but only slight to fair levels of agreement between the SJ and DJ (Kappa = ?0.26 to 0.18) and CMJ and DJ (Kappa = ?0.13 to 0.26) tests. These results highlight that the mean asymmetry value may be a poor indicator of true variability of between-limb differences in healthy athletes. The direction of asymmetry may provide a useful monitoring tool for practitioners in healthy athletes, when no obvious between-limb deficit exists. 相似文献