A statistical information-based clustering approach in distance space

Clustering, as a powerful data mining technique for discovering interesting data distributions and patterns in the nderlying database, is used in many fields, such as statistical data analysis, pattern recognition, image processing, and other usiness applications. Density-based Spatial Clustering of Applications with Noise (DBSCAN) (Ester et al., 1996) is a good erformance clustering method for dealing with spatial data although it leaves many problems to be solved. For example, BSCA…     

Using Greedy algorithm:DBSCAN revisited Ⅱ

The density-based clustering algorithm presented is different from the classical Density-Based Spatial Clustering of Applications with Noise(DBSCAN)(Ester et al.,1996),and has the following advantages: first,Greedy algorithm substitutes for R*-tree(Bechmann et al.,1990)in DBSCAN to index the clustering space so that the clustering time cost is decreased to great extent and I/O memory load is reduced as well; second,the merging condition to approach to arbitrary-shaped clusters is designed carefully so that a single threshold can distinguish correctly all clusters in a large spatial dataset though some density-skewed clusters live in it. Finally,authors investigate a robotic navigation and test two artificial datasets by the proposed algorithm to verify its effectiveness and efficiency.     

Using Greedy algorithm: DBSCAN revisited II

INTRODUCTION Clustering groups dataset data into meaning-ful subclasses in such a way that minimizes theintra-differences and maximizes the in-ter-differences of these subclasses; and is one ofthe most widely studied problems in data mining.There are many application areas for clusteringtechniques, such as statistical data analysis, patternrecognition, image processing, and other businessprocesses etc. Many clustering algorithms havebeen proposed, in part…     

Using Greedy algorithm: DBSCAN revisited II

The density-based clustering algorithm presented is different from the classical Density-Based Spatial Clustering of Applications with Noise (DBSCAN) (Esteret al., 1996), and has the following advantages: first, Greedy algorithm substitutes forR ^*-tree (Bechmannet al., 1990) in DBSCAN to index the clustering space so that the clustering time cost is decreased to great extent and I/O memory load is reduced as well; second, the merging condition to approach to arbitrary-shaped clusters is designed carefully so that a single threshold can distinguish correctly all clusters in a large spatial dataset though some density-skewed clusters live in it. Finally, authors investigate a robotic navigation and test two artificial datasets by the proposed algorithm to verify its effectiveness and efficiency. Project (No. 2002AA2010) supported by the Hi-Tech Research and Development Program (863) of China     

基于密度的聚类算法研究

聚类算法是数据挖掘的核心技术,基于密度的聚类是一类已经被证明非常有效的聚类方法．与DBSCAN算法作比较,文章提出了一种基于密度的聚类算法（Clustering Using Centers and Density,CUCD）．该算法是基于中心点以及密度实现的,其核心对象是根据数据分布计算出来的虚拟的点,并且核心对象的代表性随程序的执行次数而提高;经实验验证,该算法具有较好的时间效率和聚类质量．     

基于改进DBSCAN算法的异常数据处理

随着智慧农业的发展,农业生产中海量数据不断涌现。在海量数据中难免存在噪声数据,这些数据不仅难以提供有效价值,还会影响信息挖掘。针对该问题,采用基于密度的DBSCAN聚类算法进行异常数据处理。鉴于DBSCAN算法对参数敏感,结合数据集本身特性与统计学思想以绘制各点之间的距离升序曲线,预估出DBSCAN的Eps参数。仿真实验结果表明,改进算法平均准确率达到99.6%,较传统算法提高了1.7个百分点,并且在10次检测中,改进算法只有3个数据判定错误,证明该参数设置方法对异常数据处理准确率更高,稳定性也更好。     

Growth in toddlers’ Spanish,English, and conceptual vocabulary knowledge

This longitudinal study modeled growth rates, from ages 24 to 36 months, in English, Spanish, and conceptual (i.e., combination of English and Spanish vocabulary items in terms of known concepts) productive vocabulary among 36 children from low-income homes. Individual growth modeling was employed using scores from the MacArthur–Bates Communicative Development Inventory (CDI; Fenson et al., 2007) and the MacArthur Inventarios del Desarrollo de Habilidades Comunicativas (IDHC; Jackson-Maldonado et al., 2003) which were completed by parents every three months. Results demonstrate that students started out below national norms for monolinguals in English and Spanish vocabulary and their rates of growth did not allow them to reach age-appropriate levels even when applied beyond the age range for which the parent reports were designed. However, shifts toward more English use were documented. Additionally, when conceptual vocabulary growth was considered, the magnitude of the vocabulary gap relative to national norms was not as pronounced, underscoring the need attend to both languages. Theoretical, policy, and practical implications concerning dual language learning prior to formal school entry are discussed.     

Parental Authoritarian Control and Cognitive Complexity

Studies on the conceptual system proposed by Harvey et aJ (1961) suggested that the concrete mode of cognitive functioning is associated with certain developmental factors such as restricted exploration of the environment, overcontrol by parents, avoidance of uncertainty, conformity to external superimposed norms, and discouragement of independence, etc. Using the framework of Harvey, Schroder et al (1967) specified two types of training methods, one of which he called the deductive method. Parents adopting this method provide the child with ready made and fixed rules. The child is taught to avoid uncertainty by looking externally for rules. The variety of perceptions and responses available to the child is highly restricted. The environment is so structured that it is unrealistically oversimplified. Schroder et al believe that this type of training method would bring out a cognitive structure which is characterized by compartmentalization and inability to think in terms of degrees or relativeness.     

Threshold capabilities: threshold concepts and knowledge capability linked through variation theory

The Threshold Capability Integrated Theoretical Framework (TCITF) is presented as a framework for the design of university curricula, aimed at developing graduates’ capability to deal with previously unseen situations in their professional, social, and personal lives. The TCITF is a new theoretical framework derived from, and heavily dependent upon, the ideas of the Threshold Concepts Framework (Meyer and Land 2003a; Land et al. 2006) and Capability Theory (Bowden and Marton 1998; Bowden et al. 2000; Bowden 2004). Capability theory is firmly based in phenomenography and variation theory, is concerned with the development of knowledge capability, but has had limited application in practice. The threshold concepts framework has enjoyed greater acceptance by a large range of academics in many fields. This acceptance has initially focussed on analytic studies of what constitutes a threshold concept—and the location and distribution of such concepts—in a given domain. In many instances subsequent attention has focussed on issues of pedagogy and assessment, including the design of curricula. We propose a merging of capability theory and the threshold concepts framework and argue that capability and variation theories provide the ideal mechanism for developing a strong pedagogical approach based on newly emerging knowledge of the critical features of threshold concepts within different domains.     

数据挖掘领域中的聚类分析及应用

聚类是统计学的一种方法，也作为数据挖掘的一个功能被广泛地应用。本文介绍了聚类的概念、应用，主要的聚类算法。最后，针对现实中的一个具体问题，设计了一个层次型的聚类算法，其结果对相关部门具有一定的指导作用。     

DVB-S2 inner receiver design for broadcasting mode

INTRODUCTION The second generation satellite digital video broadcasting standard (ETSI, 2004) has come out recently. Compared with the previous satellite stan-dard DVB-S (ETSI, 2003), DVB-S2 has more ad-vantages, such as the 30% increase in channel capac-ity, the more reliable performance, and the more ef-ficient usage of transponders. The DVB-S2 standard has been designed having in mind the peculiarities of the satellite channel, particularly the link fading im-pairments and the …     

Conceptions d'élèves sur la notion de probabilité conditionnelle révélées par une méthode d'analyse des donn ées: Implication - similarité - corrélation

Résumé L'introduction des notions de probabilité, a fortiori celle de probabilité conditionnelle, pose un problème didactique épineux en raison de préconceptions des élèves (Fischbein et al., 1991), nées des références concr ètes indispensables à cette introduction. Ces préconceptions peuvent se renforcer en conceptions qui se posent en obstacles épistémologiques et obstacles d'origine didactique. À l'aide d'une nouvelle méthode d'analyse de donn ées — l'implication statistique — et d'une méthodologie d'emploi post-corré1ative, nous mettons en évidence ces conceptions à partir des travaux d'élèves et en explicitant des procédures de résolution de problèmes, rév é1atrices de ces conceptions.

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Students' conceptions on conditional probability revealed by a data analysis method: Implication - similarity - correlation

The introduction of notions of probability, above all conditional probability, poses a thorny problem in didactics due to student's preconceptions (Fischbein et al., 1991), stemming from the concrete references indispensable for this introduction. These preconceptions may be reinforced by conceptions which become epistemological and especially didactical obstacles. Using a new method of data analysis — statistical implication - and a method of post-correlative treatment, we reveal these conceptions using student's work, and make explicite the procedures of problem solving used, that are a reflexion of these conceptions.

     

Closing a Virtuous Circle: Reciprocal Influences Between Theory and Practice in Studies of Reading Intervention

Abstract

The authors reflect on findings from three studies of different approaches to reading intervention (Al Otaiba et al., Denton et al., and Miller et al., all found in this issue). It is argued that the science of interventions for reading disorders is advanced and that these and other related studies provide a strong evidence base for guiding educational policy in this area. Reading interventions need to be based on theories of reading development and reading difficulty. Current causal models of reading development arguably have focused almost exclusively on the cognitive processes underlying reading development and how best to remediate deficiencies in such processes. Such models are typically silent on broader influences (motivational, attentional, and socio-cultural) on learning, however. It is concluded that future theories will need to be broadened in order to develop more effective interventions for children with a variety of reading and language learning difficulties.     

The Knowledge Arena as an Extension to the Concept Map: Reflection in Action

The concept map is becoming a ubiquitous tool in education. In recent years there has been a growing interest in “diagramming” or “mapping” ideas to be learned (e.g., Jonassen et al., 1998). The approach has been championed by study skills proponents such as Buzan (1993). Maps of concepts and relationships have been used by many researchers and practitioners to help diagnose misunderstanding, improve study methods and glimpse how learners come to know. In other areas, the representation of knowledge in formalisms such as the Net greatly assisted the development of intelligent tutoring systems (e.g., Sowa, 1983). In order to better understand the claims made for its efficacy, reference to how concept maps have been used and defined will lead to a plausible explanation of the process of “off–loading” of concepts during learning or study (McAleese, 1994, 1998). In order to demonstrate the widespread application of supporting learn ers with external “learning spaces” (c.f. ISLEs/ and REALs—Grabinger et al., 1998; Grabinger & Dunlap, 1995; MacFarlane, 1993), consideration will be given in this paper to techniques that formally represent knowledge in Concept–Relationship–Concept “instances” (Fisher et al., 1990). Other techniques such as reflection journals draw on the same process but are not considered in detail here. The importance of self regulation (Zimmerman, 1990) and self-confrontation (McAleese, 1985) is highlighted in this framework. The map as a mirror or an assistant to learners is well documented (e.g., Vizcarro & Leon, 1998); the question of an external representation of thinking, in the form of a map determining what can be learned as well as what might be learned, is not yet fully known.     

Elementary Pre-Service Teacher Perceptions of the Greenhouse Effect

Environmental issues are an important topic both in national news, and in science education. Previous studies revealed that students hold many misconceptions relating to such issues as global warming, ozone depletion, and acid rain. This article expands on earlier work by Boyes et al. to examine pre-service teachers' views about these issues, especially global warming and the related term, the greenhouse effect, and the effect of their views on elementary student performance. Results support the findings of Boyes et al. that elementary education majors hold many misconceptions about these environmental issues, and these can effect their teaching of these topics in elementary classes.     

Latent Differential Equation Models for Binary and Ordinal Data

This study evaluates latent differential equation models on binary and ordinal data. Binary and ordinal data are widely used in psychology research and many statistical models have been developed, such as the probit model and the logit model. We combine the latent differential equation model with the probit model through a threshold approach, and then compare the threshold model with a naive model, which blindly treats binary and ordinal data as continuous. Simulation results suggest that the naive model leads to bias on binary data and on ordinal data with fewer than 5 levels, whereas the threshold model is unbiased and efficient for binary and ordinal data. Two example analyses on empirical binary data and ordinal data show that the threshold model also has better external validity. The R code for the threshold model is provided.     

Value-added measures of school effectiveness in the United Kingdom

Conclusion This paper has mostly focused on the performance of schools in terms of examination and test results. On their own, such results are insufficient for proper judgements about schools’ performance. Other pupil outcomes such as pupil attendance, capacity for independent learning, attitudes towards school and learning, behaviour and selfconcept are also important. School effectiveness research aims to investigate a broad range of educational outcomes. Examples of this approach are provided by the Junior School Project (Mortimore et al., 1988), the Lancashire project (Thomas & Mortimore, 1996) and the ISEP in Scotland (MacBeath & Mortimore, 1994) which involves collecting pupil, teacher and parent attitude data in addition to academic outcomes. Nevertheless, the main performance indicator for schools continues to be how successful they are at ensuring that as many pupils as possible achieve their full academic potential. Original language: English Sally Thomas (United Kingdom) Sally Thomas (United Kingdom) This research paper was completed via a grant awarded by the United Kingdom Economic and Social Science Research Council. I am very grateful for the helpful comments of my colleagues Louise Stoll, Pam Sammons, Harvey Goldstein and Hillary Street on a previous version of this paper.     

Teacher Stress as a Correlate of Attitudes Towards Responsibility and Change

Teachers today are continually charged with new responsibilities as a response to the changing world outside the school. Changes in the society at large require corresponding changes within the school if the latter is to be responsive to society's ever-changing needs. To the extent that stress experienced by teachers affects their attitudes towards responsibility and change, which in turn affect their professional performance, the importance of teacher stress cannot be over-emphasized. That twice as many teachers as other professionals in human services reported nervous strain indicates an aggravated situation (Cox et al., 1978).     

Nouns and verbs in Australian sign language: an open and shut case?

Results of the noun-verb pair comprehension and production tests from the Test Battery for Auslan Morphology and Syntax (Schembri et al., 2000) are re-presented, re-analyzed, and compared to data from two other cases also dealing with noun-verb pairs: the Auslan lexical database and a comparison of Auslan and American Sign Language (ASL) signs. The data elicited through the test battery and presented in this article confirm the existence of formationally related noun-verb pairs in Auslan in which the verb displays a single movement and the noun displays a repeated movement. The data also suggest that the best exemplars of noun-verb pairs of this type in Auslan form a distinct set of iconic (mimetic) signs archetypically based on inherently reversible actions (such as opening and shutting). This strong iconic link perhaps explains why the derivational process appears to be of limited productivity, though it does appear to have "spread" to a number of signs that appear to have no such iconicity. There appears to be considerable variability in the use of the derivational markings, particularly in connected discourse, even for signs of the "open and shut" variety. Overall, the derivational process is apparently still closely linked to an iconic base, is incipient in the grammar of Auslan, and is thus best described as only partially grammaticalized.     

Drawing on a Theoretical Model to Study Students’ Understandings of Fractions

Teaching and learning fractions has traditionally been one of the most problematic areas in primary school mathematics. Several studies have suggested that one of the main factors contributing to this complexity is that fractions comprise a multifaceted notion encompassing five interrelated subconstructs (i.e., part-whole, ratio, operator, quotient, and measure). Kieren was the first to establish that the concept of fractions is not a single construct, but consists of several interrelated subconstructs. Later on, in the early 1980s, Behr et al. built on Kieren’s conceptualization and suggested a theoretical model linking the five subconstructs of fractions to the operations of fractions, fraction equivalence, and problem solving. In the present study we used this theoretical model as a reference point to investigate students’ constructions of the different subconstructs of fractions. In particular, using structural equation modeling techniques to analyze data of 646 fifth and sixth graders’ performance on fractions, we examined the associations among the different subconstructs of fractions as well as the extent to which these subconstructs explain students’ performance on fraction operations and fraction equivalence. To a great extent, the data provided support to the associations included in the model, although, they also suggested some additional associations between the notions of the model. We discuss these findings taking into consideration the context in which the study was conducted and we provide implications for the teaching of fractions and suggestions for further research.