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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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Digital repositories require good metadata, created according to community-based principles that include provisions for interoperability. When metadata is of high quality, digital objects become sharable and metadata can be harvested and reused outside of the local system. A sample of U.S.-based repository administrators from the OpenDOAR initiative were surveyed to understand aspects of the quality and creation of their metadata, and how their metadata could improve. Most respondents (65%) thought their metadata was of average quality; none thought their metadata was high quality or poor quality. The discussion argues that increased strategic staffing will alleviate many perceived issues with metadata quality.  相似文献   
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The twenty-first century has seen unprecedented investment from governments around the world in educational technologies in schools. This paper investigates Australian teachers’ adoption and use of a popular technology that has been extensively supported by governments and school systems: the interactive whiteboard (IWB). The study suggests that a number of the barriers identified in the early days of adoption and use of this technology, such as professional support and access, still remain for many teachers, thereby impeding effective practices. The research also found that primary school teachers were using the technology in diverse ways, in contrast to secondary teachers who were using the IWB mainly for instructionist, presentational purposes. We conclude by considering various ways of reducing the effect of the identified barriers to support implementation of educational technologies in the classroom, especially the next generation of technologies promoted by governments and systems.  相似文献   
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The purpose of this study was to determine which study habits distinguish successful from unsuccessful foreign language learners. Participants were 219 college students from a variety of disciplinary backgrounds, enrolled in either Spanish, French, German or Japanese classes. A canonical discriminant analysis (F [6, 117], p < 0.0001; canonical R = 0.92) revealed that, compared to their high-performing counterparts, students with the lowest levels of foreign language performance tended to report that: (a) they frequently include a lot of irrelevant or unimportant information in their notes; (b) when they have difficulty with their assignments, they do not seek help from their instructor; (c) they put their lecture notes away after taking the test and never consult them again; (d) they have to be in the mood before attempting to study; (e) they have a tendency to doodle or to daydream when they are trying to study; and (f) they do not look up in a dictionary the meanings of words that they do not understand. Implications are discussed.  相似文献   
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The aim of this study was to examine the acute effects of prolonged static stretching (SS) on running economy. Ten male runners (VO2(peak) 60.1 +/- 7.3 ml x kg(-1) x min(-1)) performed 10 min of treadmill running at 70% VO2(peak) before and after SS and no stretching interventions. For the stretching intervention, each leg was stretched unilaterally for 40 s with each of eight different exercises and this was repeated three times. Respiratory gas exchange was measured throughout the running exercise with an automated gas analysis system. On a separate day, participants were tested for sit and reach range of motion, isometric strength and countermovement jump height before and after SS. The oxygen uptake, minute ventilation, energy expenditure, respiratory exchange ratio and heart rate responses to running were unaffected by the stretching intervention. This was despite a significant effect of SS on neuromuscular function (sit and reach range of motion, +2.7 +/- 0.6 cm; isometric strength, -5.6% +/- 3.4%; countermovement jump height -5.5% +/- 3.4%; all P < 0.05). The results suggest that prolonged SS does not influence running economy despite changes in neuromuscular function.  相似文献   
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Individuals with chronic obstructive pulmonary disease (COPD) have been shown to benefit from participation in pulmonary rehabilitation (PR) programs that include exercise training and education. Purpose: To examine the relationship between improvements in 6 minute walk distance and perceived quality of life in individuals with COPD following completion of a PR program. Methods: The records of 139 individuals completing a PR program (3 times a week for 8 weeks) were retrospectively examined. Prior to entry and upon completion of the program each individual completed a 6 minute walk test (6MWT), the SF-36 Health survey, and the UCSD Shortness of Breath Questionnaire (SOB). SF-36 results were analyzed according to 8 subscales [Physical Functioning (PF), Role Physical (RF), Bodily Pain (BP), General Health (GH), Vitality (V), Social Functioning (SF), Role Emotional (RE), and Mental Health (MH)]. Results: PR resulted in significant improvements in 6MWTdistance (Pre = 845 ± 37 ft, Post = 1127 ± 32 ft, p < 0.001), PF (p < 0.001), RF (p = 0.001), Vitality (p = 0.002), SF (p < 0.001), RE (p = 0.037), MH (p < 0.001) and SOB (Pre = 53 ± 2, Post = 47 ± 2, p < 0.001). The change in 6MWT distance was not related to changes in PF (r = 0.17), RF (r = 0.03), GH (r = 0.03), Vitality (r = −0.001), SF (r = 0.01), RE (r = 0.06), MH (r = −0.04) or SOB (r = 0.12). The magnitude of improvement in 6MWT distance (68%) was much greater than that observed in PF (15%), RF (16%), GH (6%), VT (18%), SF (20%), RE (14%), MH (14%), or SOB (8%). Conclusions: PR has a positive impact on 6 minute walk distance and perceived quality of life in individuals with COPD; however, changes in 6 minute walk distance appear to have no relationship to changes in perceived quality of life.  相似文献   
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