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Travis Gagie Aleksi Hartikainen Kalle Karhu Juha Kärkkäinen Gonzalo Navarro Simon J. Puglisi Jouni Sirén 《Information Retrieval》2017,20(3):253-291
Most of the fastest-growing string collections today are repetitive, that is, most of the constituent documents are similar to many others. As these collections keep growing, a key approach to handling them is to exploit their repetitiveness, which can reduce their space usage by orders of magnitude. We study the problem of indexing repetitive string collections in order to perform efficient document retrieval operations on them. Document retrieval problems are routinely solved by search engines on large natural language collections, but the techniques are less developed on generic string collections. The case of repetitive string collections is even less understood, and there are very few existing solutions. We develop two novel ideas, interleaved LCPs and precomputed document lists, that yield highly compressed indexes solving the problem of document listing (find all the documents where a string appears), top-k document retrieval (find the k documents where a string appears most often), and document counting (count the number of documents where a string appears). We also show that a classical data structure supporting the latter query becomes highly compressible on repetitive data. Finally, we show how the tools we developed can be combined to solve ranked conjunctive and disjunctive multi-term queries under the simple \({\textsf{tf}}{\textsf{-}}{\textsf{idf}}\) model of relevance. We thoroughly evaluate the resulting techniques in various real-life repetitiveness scenarios, and recommend the best choices for each case. 相似文献
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Using Differential Item Functioning Procedures to Explore Sources of Item Difficulty and Group Performance Characteristics 总被引：1，自引：0，他引：1
Statistics used to detect differential item functioning can also reflect differential strengths and weaknesses in the performance characteristics of population subgroups. In turn, item features associated with the differential performance patterns are likely to reflect some facet of the item task and hence its difficulty, that might previously have been overlooked. In this study, several item features were identified and coded for a large number of reading comprehension items from the two admissions testing programs. Item features included subject matter content, various properties of item structure, cognitive demand indicators, and semantic content (propositional analysis). Differential item functioning was evaluated for males and females and for White and Black examinees. Results showed a number of significant relationships between item features and indicators of differential item functioning—many of which were consistent across testing programs. Implications of the results for related areas of research are discussed. 相似文献
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Kalle Juuti Jari Lavonen Anna Uitto Reijo Byman Veijo Meisalo 《International Journal of Science and Mathematics Education》2010,8(4):611-632
Students find science relevant to society, but they do not find school science interesting. This survey study analyzes Finnish
grade 9 students’ actual experiences with science teaching methods and their preferences for how they would like to study
science. The survey data were collected from 3,626 grade 9 students (1,772 girls and 1,832 boys) across randomly sampled secondary
schools. Students were asked to evaluate how often a particular teaching method is used in science (chemistry and physics)
teaching and how often they would like to see the teaching method used. Data were analyzed using nonparametric tests. Boys
seemed to be more satisfied with current and traditional science teaching methods like direct teaching, solving basic problems,
reading textbooks, and conducting practical work, while girls desired more discussion. Students who are interested in school
science or think that school science is relevant in everyday life would like more creative activities such as brainstorming
and project work. Results indicated that understanding the connection between student interest and teaching method preferences,
especially interpreting interested students’ desire for creative activities, are important aspects for future research. 相似文献
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Information systems researchers that apply critical social perspectives frequently emphasize the potential for information technology to serve as a mechanism for increased rationalization, domination, and control. Such theorists often overlook or discount the liberating aspects of information systems. In this study, we apply the ideal of rational discourse developed by Jürgen Habermas to the phenomenon of Wikipedia in an effort to explore empirically the emancipatory potential of information systems. We contend that Wikipedia embodies an approximation of the necessary conditions for rational discourse. While several challenges persist, the example of Wikipedia illustrates the positive potential of information systems in supporting the emergence of more emancipatory forms of communication. The corresponding implications for researchers and design professionals alike are discussed. 相似文献
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Anni Loukomies Dimitris Pnevmatikos Jari Lavonen Anna Spyrtou Reijo Byman Petros Kariotoglou Kalle Juuti 《Research in Science Education》2013,43(6):2517-2539
This study aimed to design a teaching sequence for science education that enabled lower secondary school students to enhance their motivation towards science. Further, it looked to examine the way the designed teaching sequence affected students with different motivational profiles. Industry site visits, with embodied theory-based motivational features were included as part of the designed teaching sequence. The sequence was implemented in Finland and Greece with 54 participants, 27 from each country. Quantitative data was collected using the Evaluation of Science Inquiry Activities Questionnaire, based on the Intrinsic Motivation Inventory but did not map the expected outcomes. Interviews, however, showed that students with different motivational profiles found aspects within the module that met their psychological needs as explained by Self-Determination Theory. The results offer a perspective to adolescents’ psychological needs along with some insights into how students mediate the way they value an activity in the context of science education. 相似文献
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Inkinen Janna Klager Christopher Schneider Barbara Juuti Kalle Krajcik Joseph Lavonen Jari 《International Journal of Science Education》2019,41(3):316-329
This study examines the association between student situational engagement and classroom activities in secondary school science classrooms in Finland and the U.S. Situational engagement is conceptualised as times when students feel that a task is interesting and challenging to them and that they have the skills to complete it (see Schneider et al., 2016. Investigating optimal learning moments in U.S. and Finnish science classes. Journal of Research in Science Teaching, 53(3), 400–421. doi:10.1002/tea.21306). Data on situational engagement and classroom activities were obtained using the experience sampling method (ESM) from 247 Finnish students in 13 secondary science classrooms and 281 U.S. students in 18 secondary science classrooms. In both samples, the students tended to be situationally engaged only a small proportion of the time during their science classes. However, the Finnish students were more likely than the U.S. students to report being situationally engaged. To investigate when the students were most likely to report being situationally engaged, hierarchical logistic regression models were employed, which suggested that some classroom activities were associated with higher levels of student situational engagement than others. The Finnish students were more likely to report being situationally engaged when calculating and presenting scientific information. In the U.S., the students were more likely to report being situationally engaged while discussing scientific information and less likely when listening to the teacher. The results suggest that situational engagement is momentary and associated with specific science classroom activities. 相似文献
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This article focuses on class blogs and presents results from 1:1 schools in Sweden. While Swedish schools are increasingly using Web 2.0 technologies (e.g., wikis and blogs), most of this use is still at an experimental stage. To further the understanding of how blogs are and can be used, we compare class blogs used in practice with the fast-growing literature in the field. Previous work suggests eight uses: collaboration, making assignments, journal writing, instruction, posting supplemental material, community building, external readers, and prompting. In practice, we found blogs to be used in a fairly narrow way—mainly for instruction and posting supplemental material. We hope that this article will inspire teachers to further their blog use. 相似文献
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Anni Loukomies Kalle Juuti Jari Lavonen 《International Journal of Science Education》2013,35(18):3015-3037
Pupils’ interest has been one of the major concerns in science education research because it can be seen as a gateway to more personalised forms of interest and motivation. However, methods to investigate situational interest in science teaching and learning are not broadly examined. This study compares the pupils’ observed situational interest and their expressed situational interest. One class of Finnish fourth-graders (N?=?22, age 9–10 years) participated in a heat transfer lesson. The lesson encompassed an interactive demonstration with a thermal camera, teacher-led discussions and the conduct and presentation of a collaborative inquiry task. Pupils expressed their interest levels (scale: 1?=?very boring, 5?=?very interesting) by using an electronic response system called a ‘clicker’. The measurement took place 15 times during the lesson, with 1 measurement being just a rehearsal. The lesson was video recorded, and visible aspects of interest at the measurement time points were analysed. Reported and observational data were compared. In most cases, the observations did not yield data compatible with the pupils’ own evaluations, indicating that most pupils’ expressed interest is not easily interpreted through observation of their facial expressions and behaviour. In general, the interest of the group as a whole seems to diminish during the lesson. We argue that in order to maintain and increase pupils’ interest, their evaluations should be taken into account in lesson planning. Video-based research might also be further enriched and validated by employing the participants’ own expressions. The clicker is a suitable means of collecting primary pupils’ experiences concerning their interest levels. 相似文献