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71.
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
72.
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
73.
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
74.
Harrell Pamela Esprvalo 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
75.
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
76.
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
77.
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
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