The sum of its parts: reducing sparsity in click estimation with query segments     

Dustin Hillard  Eren Manavoglu  Hema Raghavan  Chris Leggetter  Erick Cantú-Paz  Rukmini Iyer 《Information Retrieval》2011,14(3):315-336

The critical task of predicting clicks on search advertisements is typically addressed by learning from historical click data. When enough history is observed for a given query-ad pair, future clicks can be accurately modeled. However, based on the empirical distribution of queries, sufficient historical information is unavailable for many query-ad pairs. The sparsity of data for new and rare queries makes it difficult to accurately estimate clicks for a significant portion of typical search engine traffic. In this paper we provide analysis to motivate modeling approaches that can reduce the sparsity of the large space of user search queries. We then propose methods to improve click and relevance models for sponsored search by mining click behavior for partial user queries. We aggregate click history for individual query words, as well as for phrases extracted with a CRF model. The new models show significant improvement in clicks and revenue compared to state-of-the-art baselines trained on several months of query logs. Results are reported on live traffic of a commercial search engine, in addition to results from offline evaluation.  相似文献   

Agreement in activity energy expenditure assessed by accelerometer and self-report in adolescents: variation by sex, age, and weight status     

Machado-Rodrigues AM  Coelho-E-Silva MJ  Mota J  Cyrino E  Cumming SP  Riddoch C  Beunen G  Malina RM 《Journal of sports sciences》2011,29(14):1503-1514

The agreement between self-reported and objective estimates of activity energy expenditure was evaluated in adolescents by age, sex, and weight status. Altogether, 403 participants (217 females, 186 males) aged 13-16 years completed a 3-day physical activity diary and wore a GT1M accelerometer on the same days. Partial correlations (controlling for body mass) were used to determine associations between estimated activity energy expenditure (kcal · min(-1)) from the diary and accelerometry. Differences in the magnitude of the correlations were examined using Fisher's r to z transformations. Bland-Altman procedures were used to determine concordance between the self-reported and objective estimates. Partial correlations between assessments of activity energy expenditure (kcal · min(-1)) did not differ significantly by age (13-14 years: r = 0.41; 15-16 years: r = 0.42) or weight status (normal weight: r = 0.42; overweight: r = 0.39). The magnitude of the association was significantly affected by sex (Δr = 0.11; P < 0.05). The agreement was significantly higher in males than in females. The relationship between activity energy expenditure assessed by the objective method and the 3-day diary was moderate (controlling for weight, correlations ranged between 0.33 and 0.44). However, the 3-day diary revealed less agreement in specific group analyses; it markedly underestimated activity energy expenditure in overweight/obese and older adolescents. The assessment of activity energy expenditure is complex and may require a combination of methods.  相似文献   

Prosocial and antisocial behavior in sport: the role of coaching style, autonomous vs. controlled motivation, and moral disengagement     

Hodge K  Lonsdale C 《运动与训练心理学杂志》2011,33(4):527-547

The purpose of this study was to examine whether the relationships between contextual factors (i.e., autonomy-supportive vs. controlling coaching style) and person factors (i.e., autonomous vs. controlled motivation) outlined in self-determination theory (SDT) were related to prosocial and antisocial behaviors in sport. We also investigated moral disengagement as a mediator of these relationships. Athletes' (n = 292, M = 19.53 years) responses largely supported our SDT-derived hypotheses. Results indicated that an autonomy-supportive coaching style was associated with prosocial behavior toward teammates; this relationship was mediated by autonomous motivation. Controlled motivation was associated with antisocial behavior toward teammates and antisocial behavior toward opponents, and these two relationships were mediated by moral disengagement. The results provide support for research investigating the effect of autonomy-supportive coaching interventions on athletes' prosocial and antisocial behavior.  相似文献   

Are Elementary Preservice Teachers Floating or Sinking in Their Understanding of Buoyancy?     

Harrell  Pamela Espr&#;valo  Kirby  Benjamin  Subramaniam  Kartheyan  Long  Chris 《International Journal of Science and Mathematics Education》2022,20(2):299-320

International Journal of Science and Mathematics Education - This research study investigated conceptions about buoyancy held by 55 elementary preservice teachers enrolled in a science methods...  相似文献   

Using Drawing Technology to Assess Students’ Visualizations of Chemical Reaction Processes     

Hsin-Yi Chang  Chris Quintana  Joseph Krajcik 《Journal of Science Education and Technology》2014,23(3):355-369

In this study, we investigated how students used a drawing tool to visualize their ideas of chemical reaction processes. We interviewed 30 students using thinking-aloud and retrospective methods and provided them with a drawing tool. We identified four types of connections the students made as they used the tool: drawing on existing knowledge, incorporating dynamic aspects of chemical processes, linking a visualization to the associated chemical phenomenon, and connecting between the visualization and chemistry concepts. We also compared students who were able to create dynamic visualizations with those who only created static visualizations. The results indicated a relationship between students constructing a dynamic view of chemical reaction processes and their understanding of chemical reactions. This study provides insights into the use of visualizations to support instruction and assessment to facilitate students’ integrated understanding of chemical reactions.  相似文献   

Suicidal Behavior and Help Seeking Among Diverse College Students          下载免费PDF全文

Chris Brownson  Martin Swanbrow Becker  Richard Shadick  Shanna S. Jaggars  Yael Nitkin‐Kaner 《Journal of College Counseling》2014,17(2):116-130

Suicidal and help‐seeking behaviors of students of color remain a significant problem on college campuses. Self‐reported suicidal experiences and help‐seeking behavior of diverse students are examined on the basis of results from a national survey of college student mental health. The results suggest significant differences in the expression of suicidal thoughts and behavior across racial and ethnic groups and different experiences in their referral for, and utilization of, professional help.  相似文献   

Knowledge and Dignity in the Era of “Big Data”     

Siva Vaidhyanathan  Chris Bulock 《期刊图书馆员》2014,66(1-4):49-64

Private companies and government agencies are now creating and tapping into vastly more data than ever before. These data flows include enormous amounts of personal information and raise questions about privacy and intellectual policy that could have profound impacts on our lives. While data collection and creation are nearly ubiquitous, the instruments of collection and analysis are often hidden in order to track more natural behavior. Recent revelations of massive governmental data collection offer the country, and librarians in particular, an opportunity to discuss and question the societal implications of “Big Data,” and the policies that govern them.  相似文献   

The OECD, Globalisation and Education Policy: Miriam Henry, Bob Lingard, Fazal Rizvi and Sandra Taylor. IAU Press and Pergamon. Oxford. 2001. ISBN 0-08-043449-5pp. xiii + 197. No price given     

Chris Duke 《International Journal of Educational Development》2003,23(6):688-689

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Book reviews     

David Stoker  Richard W. Clement  Pamela K. Gilbert  Charles Johanningsmeier  Janet L. Flowers  Joan Mulholland  Richard C. Rowson  David Kaser  Thomas L. Bonn  Carl B. Holmberg  Chris R. Vanden Bossche  Beth Luey  Rebecca Moore Howard 《Publishing Research Quarterly》1995,11(1):78-101

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'I never thought they would enjoy the fun of science just like ordinary children do'– Exploring science experiences with early years teacher training students and children with severe and profound learning difficulties     

Alison Bishop  & Phyllis Jones 《British Journal of Special Education》2003,30(1):34-43

Alison Bishop and Phyllis Jones both work in the School of Education at Northumbria University where they teach on undergraduate and postgraduate programmes. Phyllis Jones specialises in disability issues and Alison Bishop focuses on early years education. For the project described in this paper, they combined their areas of expertise, devising a small–scale research project to explore the experiences of a group of early years science specialist student teachers as they took part in workshops with a group of early years children with severe and profound learning difficulties. The research explores the changing attitudes and perceptions of the students with regard to the learning and teaching of science with young children. It becomes clear that there is a realization for many students that science can make a significant contribution to the education of children with severe and profound learning difficulties in the early years. The authors also discuss the need for training to equip the students to meet the challenges and rewards of working with children with severe and profound learning difficulties in their future teaching careers.  相似文献