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Traditional Cranfield test collections represent an abstraction of a retrieval task that Sparck Jones calls the “core competency” of retrieval: a task that is necessary, but not sufficient, for user retrieval tasks. The abstraction facilitates research by controlling for (some) sources of variability, thus increasing the power of experiments that compare system effectiveness while reducing their cost. However, even within the highly-abstracted case of the Cranfield paradigm, meta-analysis demonstrates that the user/topic effect is greater than the system effect, so experiments must include a relatively large number of topics to distinguish systems’ effectiveness. The evidence further suggests that changing the abstraction slightly to include just a bit more characterization of the user will result in a dramatic loss of power or increase in cost of retrieval experiments. Defining a new, feasible abstraction for supporting adaptive IR research will require winnowing the list of all possible factors that can affect retrieval behavior to a minimum number of essential factors. 相似文献
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Richard A. Voorhees 《Research in higher education》1985,22(1):65-92
Lisrel, a more versatile technique than traditional path analysis, was employed to account for 42% of the variance in the persistence of 343 new freshman financial aid recipients at a major urban university. Unlike recent persistence models, the specific model developed here highlights the impact of student finances—in particular, the amount of assistance from the programs of federal campus-based aid—on the persistence of freshmen with high financial need. The results indicate that financial need, student residency status, and noncampus-based loans and grants have direct effects on new freshman persistence regardless of the type or amount of campus-based aid awarded. The direct effect of each federal campus-based program on persistence was significant and positive. Implications for administrators and persistence researchers are discussed.Expanded version of a paper presented at the 24th Annual Forum of the Association for Institutional Research, Fort Worth, Tex., May 1984. 相似文献
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Searching hierarchically clustered document collections can be effective[6], but creating the cluster hierarchies is expensive, since there are both many documents and many terms. However, the information in the document-term matrix is sparse: Documents are usually indexed by relatively few terms. This paper describes the implementations of three agglomerative hierarchic clustering algorithms that exploit this sparsity so that collections much larger than the algorithms' worst case running times would suggest can be clustered. The implementations described in the paper have been used to cluster a collection of 12,000 documents. 相似文献
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Two experiments evaluating the effects of external stimuli on attack and biting in rats elicited by electric tailshock are reported. In the first experiment, stimuli presented to four groups of test subjects consisted of a stimulus animal, a stimulus animal plus taped vocalizations of a rat experiencing shock, an inanimate object, and an inanimate object plus taped vocalizations. Subjects in a fifth (control) group were tested in the absence of these stimuli. The presence of another animal in the test situation significantly increased the amount of target-directed responding. A decrease in responding, rather than increase, was shown by the subjects tested under the stimulus-object plus taped-vocalization conditions. Experiment 2 investigated the salient features of the stimulus animal and found a combination of both olfactory and visual cues to be most effective in eliciting target-directed responding. These studies indicate that the amount of target-directed attack and biting shown in this situation may be related causally to the type of sensory input received by the test animal. 相似文献
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Richard A. Voorhees 《Research in higher education》1987,26(2):115-129
Logit modeling was developed to explore the persistence of community college students. Independent variables included student demographic characteristics, purpose for enrolling, intention to return, frequency of informal interaction with faculty, and satisfaction with the college. Four separate models posited in this study indicate that persistence was a function of sex, purpose for enrolling, and intention to return. A posited model of academic integration indicated that measures of academic integration, including grade-point average, number of hours spent studying each week, and frequency of informal interaction with faculty were independent of persistence. A synopsis of the connections between the findings reported here and conceptual models of persistence focusing on four-year colleges and universities is presented.Based on a paper presented at the Twenty-Sixth Annual Forum of the Association for Institutional Research, Orlando, Fla., June 23, 1986. 相似文献
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TREC genomics special issue overview 总被引：1，自引：0，他引：1
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A known-item search is a particular information retrieval task in which the system is asked to find a single target document in a large document set. The TREC-5 confusion track used a set of 49 known-item tasks to study the impact of data corruption on retrieval system performance. Two corrupted versions of a 55,600 document corpus whose true content was known were created by applying OCR techniques to page images. The first version of the corpus used the page images as scanned, resulting in an estimated character error rate of approximately 5%. The second version used page images that had been down-sampled, resulting in an estimated character error rate of approximately 20%. The true text and each of the corrupted versions were then searched using the same set of 49 questions. In general, retrieval methods that attempted a probabilistic reconstruction of the original clean text fared better than methods that simply accepted corrupted versions of the query text. 相似文献