A study of results overlap and uniqueness among major Web search engines     

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   

Almost thinking counterfactually: children's understanding of close counterfactuals     

Beck SR  Guthrie C 《Child development》2011,82(4):1189-1198

Saying something "almost happened" indicates that one is considering a close counterfactual world. Previous evidence suggested that children start to consider these close counterfactuals at around 2 years of age (P. L. Harris, 1997), substantially earlier than they pass other tests of counterfactual thinking. However, this success appears to result from false positives. In Experiment 1 (N = 41), 3- and 4-year-olds could identify a character who almost completed an action when the comparison did not complete it. However, in Experiments 1 and 2 (N = 98), children performed poorly when the comparison character completed the action. In Experiment 3 (N = 28), 5- and 6-year-olds consistently passed the task, indicating that they made appropriate counterfactual interpretations of the "almost" statements. This understanding of close counterfactuals proved more difficult than standard counterfactuals.  相似文献   

Using digital images of the zebra finch song system as a tool to teach organizational effects of steroid hormones: a free downloadable module     

Grisham W  Schottler NA  McCauley LM  Pham AP  Ruiz ML  Fong MC  Cui X 《CBE life sciences education》2011,10(2):222-230

Zebra finch song behavior is sexually dimorphic: males sing and females do not. The neural system underlying this behavior is sexually dimorphic, and this sex difference is easy to quantify. During development, the zebra finch song system can be altered by steroid hormones, specifically estradiol, which actually masculinizes it. Because of the ease of quantification and experimental manipulation, the zebra finch song system has great potential for use in undergraduate labs. Unfortunately, the underlying costs prohibit use of this system in undergraduate labs. Further, the time required to perform a developmental study renders such undertakings unrealistic within a single academic term. We have overcome these barriers by creating digital tools, including an image library of song nuclei from zebra finch brains. Students using this library replicate and extend a published experiment examining the dose of estradiol required to masculinize the female zebra finch brain. We have used this library for several terms, and students not only obtain significant experimental results but also make gains in understanding content, experimental controls, and inferential statistics (analysis of variance and post hoc tests). We have provided free access to these digital tools at the following website: http://mdcune.psych.ucla.edu/modules/birdsong.  相似文献   

Medical students' attitudes toward the anatomy dissection room in relation to personality     

Plaisant O  Courtois R  Toussaint PJ  Mendelsohn GA  John OP  Delmas V  Moxham BJ 《Anatomical sciences education》2011,4(6):305-310

Assessment of the personalities of medical students could enable medical educators to formulate strategies for the best development of academic and clinical competencies. In this article, we focus on the experience of students in the anatomy dissecting room. While there have been many attempts to evaluate the emotional responses of medical students to human cadaveric dissection, there has been no investigation into how different personality traits affect the responses. The main hypothesis tested was that there is a relationship between personality traits and attitudes toward the dissection room. For the present study, a group of French medical students (n = 403; mean age 21.3 ± 1.6; 65.3% female) completed a "Big Five" personality inventory and a questionnaire to assess their attitudes in regard to human dissection. The findings are consistent with our hypothesis, in that we found a relationship between reporting anxiety and four of the "Big Five" dimensions (all except openness). The rated level of anxiety was positively correlated with negative affectivity, more strongly at the beginning than at the end of the course. There were significant gender differences in attitudes toward dissection. The findings are discussed in relation to the possibility of preparing students for the dissecting room experience and also in relation to the students' understanding of mortality issues.  相似文献   

Real time search on the web: Queries,topics, and economic value     

Bernard J. Jansen  Zhe Liu  Courtney Weaver  Gerry Campbell  Matthew Gregg 《Information processing & management》2011

Real time search is an increasingly important area of information seeking on the Web. In this research, we analyze 1,005,296 user interactions with a real time search engine over a 190 day period. Using query log analysis, we investigate searching behavior, categorize search topics, and measure the economic value of this real time search stream. We examine aggregate usage of the search engine, including number of users, queries, and terms. We then classify queries into subject categories using the Google Directory topical hierarchy. We next estimate the economic value of the real time search traffic using the Google AdWords keyword advertising platform. Results shows that 30% of the queries were unique (used only once in the entire dataset), which is low compared to traditional Web searching. Also, 60% of the search traffic comes from the search engine’s application program interface, indicating that real time search is heavily leveraged by other applications. There are many repeated queries over time via these application program interfaces, perhaps indicating both long term interest in a topic and the polling nature of real time queries. Concerning search topics, the most used terms dealt with technology, entertainment, and politics, reflecting both the temporal nature of the queries and, perhaps, an early adopter user-based. However, 36% of the queries indicate some geographical affinity, pointing to a location-based aspect to real time search. In terms of economic value, we calculate this real time search stream to be worth approximately US $33,000,000 (US $33 M) on the online advertising market at the time of the study. We discuss the implications for search engines and content providers as real time content increasingly enters the main stream as an information source.  相似文献   

“国际科学书系”与达尔文主义的传播     

莱特曼 《科学文化评论》2011,8(5):69-80

在本文中我考察了“国际科学书系”作为出版界的一个独特的试验,在它存在的过程中是否传播了达尔文主义关于科学与宗教的关系的观念。赫胥黎、丁铎尔、斯宾塞和尤曼斯是国际科学书系创办之初的关键人物,他们都是进化论的自然主义者,对于科学与宗教的关系共同持有一种复杂的看法。虽然国际科学书系最初是一个致力于传播进化论自然主义的出版项目,但我将论证,到19世纪80年代初,当该系列最初的创办者们丧失对它的控制时,一条新的路线方针被建立起来。  相似文献   

Trained humans can exercise safely in extreme dry heat when drinking water ad libitum     

Nolte HW  Noakes TD  Van Vuuren B 《Journal of sports sciences》2011,29(12):1233-1241

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Promoting Inquiry-Based Teaching in Laboratory Courses: Are We Meeting the Grade?     

Christopher Beck  Amy Butler  Karen Burke da Silva 《CBE life sciences education》2014,13(3):444-452

Over the past decade, repeated calls have been made to incorporate more active teaching and learning in undergraduate biology courses. The emphasis on inquiry-based teaching is especially important in laboratory courses, as these are the courses in which students are applying the process of science. To determine the current state of research on inquiry-based teaching in undergraduate biology laboratory courses, we reviewed the recent published literature on inquiry-based exercises. The majority of studies in our data set were in the subdisciplines of biochemistry, cell biology, developmental biology, genetics, and molecular biology. In addition, most exercises were guided inquiry, rather than open ended or research based. Almost 75% of the studies included assessment data, with two-thirds of these studies including multiple types of assessment data. However, few exercises were assessed in multiple courses or at multiple institutions. Furthermore, assessments were rarely based on published instruments. Although the results of the studies in our data set show a positive effect of inquiry-based teaching in biology laboratory courses on student learning gains, research that uses the same instrument across a range of courses and institutions is needed to determine whether these results can be generalized.  相似文献   

Testing and Teacher Certification: An Explosive Combination     

Rita Hodgkins  Bernard McKenna 《Educational Measurement》1982,1(2):10-12

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Learning and development: Contributions from Vygotsky’s theory     

Michel Brossard  Bernard Schneuwly 《European Journal of Psychology of Education - EJPE》1994,9(4):279-280

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