Measuring Search Engine Quality   总被引：12，自引：3，他引：9  

David Hawking  Nick Craswell  Peter Bailey  Kathleen Griffihs 《Information Retrieval》2001,4(1):33-59

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   

Medical history for tomorrow—preserving the record of today     

David Pearson 《Health information and libraries journal》2001,18(3):139-143

This paper addresses the need to recognize the importance, and the challenges, of preserving the hugely expanding record of medicine today for historians of the future. We are faced not only with an increase in traditional publishing formats, but also with the rapid growth in electronic communications. Two celebrated medical cases, one from the late seventeenth century and one from the late twentieth, are used to illustrate the differences and the difficulties. The need for active and effective professional collaboration is stressed; libraries should work together to address these issues.  相似文献   

'Peace studies’ and ‘education’: a rejoinder to Scruton     

David Aspin 《Cambridge Journal of Education》1987,17(1):12-19

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Force transducer system for measurement of ice hockey skating force     

Tyler J. Stidwill  Rene Albert Turcotte  Phil Dixon  David J. Pearsall 《Sports Engineering》2009,12(2):63-68

The purpose of this study was to develop a portable force measurement system for ice hockey skating. The system consisted of three strain gauge pairs affixed to an ice hockey skate’s blade holder with wire leads connected to a microprocessor controlled data acquisition device carried in a backpack worn by the skater. The configuration of the strain gauges simultaneously determined the vertical and medial–lateral force components experienced by the blade holder with a resolution accuracy of 1.9 N and a coefficient of variation of 9.2%. On-ice testing of this system with subjects performing forward start, acceleration, and constant velocity skating permitted unencumbered, natural movement and demonstrated clear, unambiguous signal responses, high trial-to-trial repeatability, and easy data retrieval. The practicality and accuracy of this testing approach have many applications, such as a quantitative tool for skating force assessment to aid athletes and coaches, as well as providing the means to examine other skill-specific dynamics.  相似文献   

The effect of primary cosmic-ray energy upon burst production     

W.F.G. SwannD.B. Cowie 《Journal of The Franklin Institute》1937

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Observations on siemens' unit     

F. Kohlrausch 《Journal of The Franklin Institute》1871,91(5):349-355

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Developing the evidence base for UK film strategy: the research process at the UK Film Council     

David Steele 《Cultural Trends》2004,13(4):5-21

The UK Film Council established a Research and Statistics Unit in order to gather data relating to film to inform the development of UK Film Council strategy and to provide an information service to the industry, government, the arts and cultural sector and the wider research community. The Research and Statistics Unit draws data from both official and unofficial sources and commissions its own special-purpose studies to gather information relevant to the strategic objectives of the Council. Key tasks are the measurement of the size of the market for film and the various elements of the film value chain, the performance of films supported by the UK Film Council and the performance of UK films in general. Special-purpose research projects currently include a detailed survey of the film production workforce, a study of the economic impact of the UK screen industries and studies of the social impact of local cinemas and the experience of Black- and Minority-led film production companies. A range of industry and official partners are collaborating in these studies. The Research and Statistics Unit also provides statistical and policy analysis relating to the wider policy environment of UK film, including issues such as the future of film tax incentives. This analysis has been developed within the HM Treasury ‘Green Book’ framework with particular reference to understanding market failure in relation to film. Central to the market failure argument is the cultural value of film in both its qualitative and its quantitative aspects. UK Film Council research is placed in the context of the literature on hedonic pricing and contingent valuation. The industrial challenges of increasing cultural value are discussed. Finally, consideration is given to the potential of film to contribute directly to ‘public value’.  相似文献   

Development of maximal oxygen uptake in young elite male cross-country skiers: a longitudinal study.     

F Ingjer 《Journal of sports sciences》1992,10(1):49-63

The aim of this study was to investigate the effects of extensive endurance training (15-25 h per week) on the development of maximal oxygen uptake (VO2 max) in boys from puberty. Maximal oxygen uptake was measured a number of times each year from the age of puberty and for the next 6-9 years in seven young male elite cross-country skiers. Mean VO2 max was measured as 76.3 and 80.1 ml kg-1 min-1 at the ages of 14 and 15 years respectively. Despite the fast rate of growth during puberty, maximal aerobic power showed seasonal variations from the age of 14, reaching a plateau at the age of 15, whereas VO2 max (ml kg-2/3 min-1) increased continuously. It is concluded that, during puberty, boys probably attain significant increases in VO2 max when appropriate amounts of endurance training are undertaken.  相似文献   

Editorial: Critical Studies and the Museum of Contemporary Art     

David Thistlewood 《The International Journal of Art & Design Education》1987,6(2):123-129

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Teachers, Language Study and Linguistics: A Contrast in Strategies     

David Westgate 《English in Education》1987,21(3):58-62

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