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《British Educational Research Journal》2003,29(5):749-765
Abstract The last 20 years have seen the development of sophisticated techniques for analysing individual data within a hierarchical context and the growing availability of good datasets to which these techniques can be applied. The modelling of pupil performance controlling for prior attainment has led to a type of analysis commonly titled ‘value‐added’. Concern for school factors which affect pupil progress has given rise to ‘school effectiveness’ research. This article outlines the history of these linked movements, mainly with reference to England and Wales, but developments in other countries are also outlined. It discusses some of the objections that have been raised, and comments on possible future directions. 相似文献
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Meta-information generation in distributed information system 总被引：2，自引：0，他引：2
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针对唇语识别过程中唇部特征提取和时序关系存在的问题,提出一种卷积神经网络（CNN）和双向长短时记忆网络（Bi-LSTM）相结合的深度学习模型。利用CNN学习唇部特征,并将学习到的唇部特征送入Bi-LSTM进行时序编码,通过Softmax进行分类。建立NUMBER DATASET和PHRACE DATASET两个大型汉语数据集以解决汉语唇语数据缺失问题。将该模型与传统的唇语识别方法在两个数据集上进行实验对比,发现在NUMBER DATASET上识别准确率为81.3%,比传统方法提高了8.1%,在PHRACE DATASET上识别准确率为83.5%,比传统方法提高了9%。实验结果表明该模型能有效提高唇语识别的准确率。 相似文献
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In standard canonical correlation analysis （CCA）, the data from definite datasets are used to estimate their canonical correlation. In real applications, for example in bilingual text retrieval, it may have a great portion of data that we do not know which set it belongs to. This part of data is called unlabeled data, while the rest from definite datasets is called labeled data. We propose a novel method called regularized canonical correlation analysis （RCCA）, which makes use of both labeled and unlabeled samples. Specifically, we learn to approximate canonical correlation as if all data were labeled. Then, we describe a generalization of RCCA for the multi-set situation. Experiments on four real world datasets, Yeast, Cloud, Iris, and Haberman, demonstrate that, by incorporating the unlabeled data points, the accuracy of correlation coefficients can be improved by over 30%. 相似文献
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Fiona Q. Wood David C. Nicholls V. Lynn Meek 《The Australian Educational Researcher》1993,20(3):83-100
The 1980s have witnessed a growing concern by governments in many western countries that the research finding agencies which they support are accountable/or what is funded and can demonstrate efficiency and effectiveness of their operations. However, despite the reports regarding the operations of for example, the National Science Foundation in the United States and the Research Councils in the United Kingdom there is very little readily available information on the operations of those agencies or Programs responsible for the allocation of “seed funds”. This article reports the results of a survey which investigated how one such Program in Australia has been meeting both its own aims as well as the needs of its grant recipients in relation to collaborative international science and technology projects. The findings show an overwhelming support for the Program and identify many tangible examples of how a little money can go a long way. Furthermore, one of the main points made by grant recipients is that the Program is complementary to, rather than a supplement for the other Australian research funding schemes. 相似文献
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辐射屏蔽是辐射安全防护工作的关键环节。常规简易的辐射屏蔽手段偏重于静态防护,无法解决实验过程中的辐射防护问题。设计了一种β-固体放射源辐照装置,通过高密度材料铅与内置的低密度材料有机玻璃组合,将固体放射源固定在屏蔽装置内部的有机玻璃内,样品通过放样装置(插板)接受放射源辐照,避免了直接移动90Sr-90Yβ放射源的操作。经测试,该装置有很好的射线屏蔽效果,距屏蔽装置5 cm处和100 cm处的剂量当量率分别为6.02μSv/h和0.28μSv/h,远低于国家标准限值,能够有效保证操作过程中实验人员的人身安全,对于辐照装置的屏蔽设计及β-固体放射源放射安全防护具有一定参考意义。 相似文献
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Data on learning outcomes is essential for tracking progress in achieving education goals, understanding what education policies work (and don’t work), and holding public officials accountable. We assess the accuracy and reliability of India’s two nationally representative surveys on learning outcomes, ASER and NAS, so that users of these datasets may better understand when, and for what purposes, these two datasets can reasonably be used. After restricting our sample to maximize comparability between the two datasets, we find that NAS state averages are significantly higher than ASER state averages and averages from an independently conducted and nationally representative survey (IHDS). In addition, state rankings based on NAS data display almost no correlation with state rankings based on ASER, IHDS, or net state domestic product per capita. We conclude that NAS state averages are likely artificially high and contain little information about states’ relative performance. The presence of severe bias in the NAS data suggests that this data should be used carefully or not at all for comparisons between states, constructing learning profiles, or any other purpose. We then analyze the internal reliability of ASER data using variance decomposition methods. We find that while ASER data is mostly reliable for comparing state averages, it is less reliable for looking at district averages, or changes in district and state averages over time. We conclude that analysts may use ASER data with confidence for comparisons between states in a single year, constructing learning profiles, and assessing learning inequality but should exercise caution when comparing changes in state scores and avoid using ASER district-level data. 相似文献
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采用了理论与实践相结合的研究方法,研发设计了一套安捷伦仪表与ADS仿真系统联网数据交换的测试平台,对于3G通信网络乃至将来4G通信网络的数据交换测试,具有重要的意义。 相似文献
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空间元数据描述了地理信息中空间数据集的内容、质量、表示方式、空间参考、管理方式以及其它特征,有助于空间数据的理解、发现、定位、挖掘、评估和维护。分析了设计空间元数据的检索服务方法。 相似文献
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张红霞 《安徽广播电视大学学报》2003,(3):47-51
TEM4听写采用的是较传统的数错扣分法。数错扣分法是负分法，其中存在一些问题。因此我们提出一种实验性的评分方法——部分得分制。实验数据有两组，分别采用TEM4听写评分制和新评分制。数据比较以及部分得分模型(Rasch模型之一)对实验量表效能的分析(如模型与数据拟合值、被试拟合值、信息函数等)说明，实验评分制能较好地测量大多数学生的听写水平。 相似文献
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We present novel vector permutation and branch reduction methods to minimize the number of execution cycles for bit reversal algorithms. The new methods are applied to single instruction multiple data （SIMD） parallel implementation of complex data floating-point fast Fourier transform （FFT）. The number of operational clock cycles can be reduced by an average factor of 3.5 by using our vector permutation methods and by 1.1 by using our branch reduction methods, compared with conventional implementations. Experiments on MPC7448 （a well-known SIMD reduced instruction set computing processor） demonstrate that our optimal bit-reversal algorithm consistently takes fewer than two cycles per element in complex array operations. 相似文献
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Invention and Productive Failure activities ask students to generate methods that capture the important properties of some given data (e.g., uncertainty) before being taught the expert solution. Invention and Productive Failure activities are a class of scientific inquiry activities in that students create, implement, and evaluate mathematical models based on data. Yet, lacking sufficient inquiry skills, students often do not actualize the full potential of these activities. We identified key invention strategies in which students often fail to engage: exploratory analysis, peer interaction, self-explanation, and evaluation. A classroom study with 134 students evaluated the effect of supporting these skills on the quality and outcomes of the invention process. Students in the Unguided Invention condition received conventional Invention Activities; students in the Guided Invention condition received complementary metacognitive scaffolding. Students were asked to invent methods for calculating uncertainties in best-fitting lines. Guided Invention students invented methods that included more conceptual features and ranked the given datasets more accurately, although the quality of their mathematical expressions was not improved. At the process level, Guided Invention students revised their methods more frequently and had more and better instances of unprompted self-explanations even on components of the activity that were not supported by the metacognitive scaffolding. Classroom observations are used to demonstrate the effect of the scaffolding on students’ learning behaviours. These results suggest that process guidance in the form of metacognitive scaffolding augments the inherent benefits of Invention Activities and can lead to gains at both domain and inquiry levels. 相似文献
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聚类分析是数据挖掘中的一个重要研究领域,面对大规模的、高维的数据,如何建立有效的聚类算法是目前一个研究热点。现已有多种直接和快速的聚类算法,但是当处理海量数据时,时间效率仍然有待提高。本文应用三角不等式原理,分别对TTSAS算法和k-means算法提出改进,避免其中冗余的距离计算,提高原算法效率。 相似文献
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David White 《PRIMUS》2019,29(9):997-1038
AbstractIn an increasingly data-driven world, facility with statistics is more important than ever for our students. At institutions without a statistician, it often falls to the mathematics faculty to teach statistics courses. This paper presents a model that a mathematician asked to teach statistics can follow. This model entails connecting with faculty from numerous departments on campus to develop a list of topics, building a repository of real-world datasets from these faculty, and creating projects where students interface with these datasets to write lab reports aimed at consumers of statistics in other disciplines. The end result is students who are well prepared for interdisciplinary research, who are accustomed to coping with the idiosyncrasies of real data, and who have sharpened their technical writing and speaking skills. 相似文献
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张洁玲 《福建工程学院学报》2017,(6):591-596
针对传统离群点检测算法的局限性进行研究,利用数据对象之间的相邻关系,提出了一种基于密度和距离相结合的离群检测算法,该算法解决了基于距离的离群检测算法不能准确识别局部离群点的问题,有效避免由于稀疏和密集簇过于邻近的而出现离群点误判的情况。通过在人工模拟数据及真实数据集上的实验测试证明改进算法的可行性,该算法能更有效地检测出数据集中的离群对象。 相似文献
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Optimal velocity functions for car-following models 总被引：1，自引：0，他引：1
The integral part of the optimal velocity car-following models is the optimal velocity function （OVF）, which can be derived from measured velocity-spacing data. This paper discusses several characteristics of the OVF and presents regression analysis on two classical datasets, the Lincoln and Holland tunnels, with different possible OVFs. The numerical simulation of the formation of traffic congestion is conducted with three different heuristic OVFs, demonstrating that these functions give results similar to those of the famous Bando OVF （Bando et al., 1995）. Also an alternative method is present for determining the sensitivity and model parameters based on a single car driving to a fixed barrier. 相似文献
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Recently a new clustering algorithm called ＇affinity propagation＇ （AP） has been proposed, which efficiently clustered sparsely related data by passing messages between data points. However, we want to cluster large scale data where the similarities are not sparse in many cases. This paper presents two variants of AP for grouping large scale data with a dense similarity matrix. The local approach is partition affinity propagation （PAP） and the global method is landmark affinity propagation （LAP）. PAP passes messages in the subsets of data first and then merges them as the number of initial step of iterations; it can effectively reduce the number of iterations of clustering. LAP passes messages between the landmark data points first and then clusters non-landmark data points; it is a large global approximation method to speed up clustering. Experiments are conducted on many datasets, such as random data points, manifold subspaces, images of faces and Chinese calligraphy, and the results demonstrate that the two approaches are feasible and practicable. 相似文献
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Social and behavioral scientists are increasingly employing technologies such as fMRI, smartphones, and gene sequencing, which yield ‘high-dimensional’ datasets with more columns than rows. There is increasing interest, but little substantive theory, in the role the variables in these data play in known processes.This necessitates exploratory mediation analysis, for which structural equation modeling is the benchmark method. However, this method cannot perform mediation analysis with more variables than observations. One option is to run a series of univariate mediation models, which incorrectly assumes independence of the mediators. Another option is regularization, but the available implementations may lead to high false-positive rates.In this article, we develop a hybrid approach which uses components of both filter and regularization: the ‘Coordinate-wise Mediation Filter’. It performs filtering conditional on the other selected mediators. We show through simulation that it improves performance over existing methods. Finally, we provide an empirical example, showing how our method may be used for epigenetic research. 相似文献