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1.
Comparing rankings of search results on the Web 总被引：1，自引：0，他引：1
The Web has become an information source for professional data gathering. Because of the vast amounts of information on almost all topics, one cannot systematically go over the whole set of results, and therefore must rely on the ordering of the results by the search engine. It is well known that search engines on the Web have low overlap in terms of coverage. In this study we measure how similar are the rankings of search engines on the overlapping results.We compare rankings of results for identical queries retrieved from several search engines. The method is based only on the set of URLs that appear in the answer sets of the engines being compared. For comparing the similarity of rankings of two search engines, the Spearman correlation coefficient is computed. When comparing more than two sets Kendall’s W is used. These are well-known measures and the statistical significance of the results can be computed. The methods are demonstrated on a set of 15 queries that were submitted to four large Web search engines. The findings indicate that the large public search engines on the Web employ considerably different ranking algorithms. 相似文献
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Amanda Spink Bernard J. Jansen Chris Blakely Sherry Koshman 《Information processing & management》2006
The performance and capabilities of Web search engines is an important and significant area of research. Millions of people world wide use Web search engines very day. This paper reports the results of a major study examining the overlap among results retrieved by multiple Web search engines for a large set of more than 10,000 queries. Previous smaller studies have discussed a lack of overlap in results returned by Web search engines for the same queries. The goal of the current study was to conduct a large-scale study to measure the overlap of search results on the first result page (both non-sponsored and sponsored) across the four most popular Web search engines, at specific points in time using a large number of queries. The Web search engines included in the study were MSN Search, Google, Yahoo! and Ask Jeeves. Our study then compares these results with the first page results retrieved for the same queries by the metasearch engine Dogpile.com. Two sets of randomly selected user-entered queries, one set was 10,316 queries and the other 12,570 queries, from Infospace’s Dogpile.com search engine (the first set was from Dogpile, the second was from across the Infospace Network of search properties were submitted to the four single Web search engines). Findings show that the percent of total results unique to only one of the four Web search engines was 84.9%, shared by two of the three Web search engines was 11.4%, shared by three of the Web search engines was 2.6%, and shared by all four Web search engines was 1.1%. This small degree of overlap shows the significant difference in the way major Web search engines retrieve and rank results in response to given queries. Results point to the value of metasearch engines in Web retrieval to overcome the biases of individual search engines. 相似文献
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毕节方言中,重叠词语众多,形式复杂。毕节人说普通话,常常会使用重叠形式的词语,因而容易导致使用方言词语讲普通话的错误。从构成方式入手,以名词、形容词、动词为主要分析对象,比较毕节方言词汇与普通话词汇中重叠形式的异同,为毕节人讲好普通话服务。 相似文献
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本文通过对国内外铝塑复合管发展状况进行比较和总结,归纳出搭接法和对接法两种工艺方法是目前现有较好的工艺方法,并展望了铝塑复合管今后的发展前景。 相似文献
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Sentence level novelty detection aims at spotting sentences with novel information from an ordered sentence list. In the task, sentences appearing later in the list with no new meanings are eliminated. For the task of novelty detection, the contributions of this paper are three-fold. First, conceptually, this paper reveals the computational nature of the task currently overlooked by the Novelty community—Novelty as a combination of partial overlap (PO) and complete overlap (CO) relations between sentences. We define partial overlap between two sentences as a sharing of common facts, while complete overlap is when one sentence covers all of the meanings of the other sentence. Second, technically, a novel approach, the selected pool method is provided which follows naturally from the PO-CO computational structure. We provide formal error analysis for selected pool and methods based on this PO-CO framework. We address the question how accurate must the PO judgments be to outperform the baseline pool method. Third, experimentally, results were presented for all the three novelty datasets currently available. Results show that the selected pool is significantly better or no worse than the current methods, an indication that the term overlap criterion for the PO judgments could be adequately accurate.
相似文献
| Shaoping MaEmail: |
6.
《Journal of Informetrics》2014,8(3):710-727
By modeling research systems as complex systems we generalize similarity measures used in the literature during the last two decades. We propose to use the mathematical tools developed within the spin-glasses literature to evaluate similarity within systems and between systems in a unified manner. Our measure is based on the ‘overlap’ of disciplinary profiles of a set of research systems and can readily be integrated in the framework of traditional bibliometric profile analysis. The investigation of the distribution of the overlaps provides useful insights on the dynamics of the general system, that is whether it converges toward a unique disciplinary structure or to a differentiated pattern.We illustrate the usefulness of the approach by investigating the dynamics of disciplinary profiles of European countries from 1996 to 2011. We analyze several bibliometric indicators (including publications and citations) of European countries in the 27 Scopus subject categories. We compare the disciplinary profiles of European countries (i) among them; (ii) with respect to the European standard; and (iii) to the World reference.We find that there is a convergence toward a unique European disciplinary profile of the scientific production even if large differences in the scientific profiles still remain. The investigation of the dynamics by year shows that developing countries are converging toward the European model while some developed countries are departing from it. 相似文献
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阿来《尘埃落定》中的“傻子”是土司制度巩固、走向瓦解的参与、思想、见证人，是作品在历史的厚重中凸显空灵的灵魂人物，他以其自我审视与历史审视的眼睛，既显示出他对土司权力的略带侥幸的患得惠失的不懈图谋，又显示出他长远瞩望不得其真的无奈，他只能无可奈何地站在广漠历史天幕下踟躇独行，矛盾重重地成了一个历史“化亡灵”的记忆。 相似文献
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Classical information retrieval and overlap measures such as the Jaccard index, the Dice coefficient and Salton’s cosine measure can be characterized by Lorenz curves. This result demonstrates the existence of a formal link between information retrieval and the information sciences on the one hand, and concentration and diversity theory, as used, e.g., in social economics and ecology on the other. 相似文献
10.
“形势与政策”课多维教学模式建构的理论与实践 总被引：1，自引：0，他引：1
“形势与政策”课是高校思想政治理论课教育教学不可缺少的组成部分,具有动态性、政策性、时效性、针对性等特点。要实现该课的实效性,必须加大改革力度,抓住课堂教学、校园文化、社会实践等多个环节,努力建构新时期“形势与政策”课多维教学模式。 相似文献