A2 Healthcare offers statistical analysis services covering various study designs. We have successfully fostered many expert staff members well-established in the biostatistics field based on satisfactory education and training programs to support those studies. Also, we have extensive experience in interim analysis, protocol development support and sample-size designing. We have continuously obtained knowledge in this area, which allows us to have the following research performance and publications in academic journals, international conferences etc.
Our statisticians have sufficient expertise to conduct analysis in Bayesian design and adaptive design. Zu, P. The authors discuss how systematic applications of statistical and psychometric methods are used to develop and evaluate scoring rules in terms of test reliability. The authors discuss applications of Multidimensional Item Response Theory MIRT models with covariates to longitudinal test data to measure skill differences at the individual and group levels.
Hao, L. Smith, R. Mislevy, A. They also propose a set of analysis methods for identifying useful information from the log files and implement the methods in a package in the Python programming language, glassPy.
Davey, S. Ferrara, P. Shavelson, N. The authors take up issues of definition; scoring, score reliability and task comparability for individual and groupwork performance assessment; and modeling and scoring of the diverse response types produced. The authors of this study propose that the unique needs and characteristics of linguistic minorities should be considered throughout the test development process, as well as strategies that focus on the early stages of test development.
Singapore: National University of Singapore, , pp. McCaffrey Observational Studies, v1, pp. The authors review approaches to consistent estimation of a population mean of an incompletely observed variable using error-prone covariates, noting difficulties with applying these methods.
McCaffrey, K. Yuan, T. Savitsky, J. Lockwood, M. Edelen Educational Measurement: Issues and Practice, v34, n2, pp. The authors examine the factor structure of scores from the CLASS-S protocol obtained from observations of middle school classroom teaching.
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- Statistical Methods for the Evaluation of Educational Services and Quality of Products | Publons!
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They demonstrate that errors in scores made by two raters on the same lesson have a factor structure that is distinct from the factor structure at the teacher level. They consider alternative hierarchical estimation approaches designed to prevent the contamination of estimated teacher-level factors. The authors establish necessary and sufficient conditions for matching and weighting with functions of observed covariates to yield unconfounded causal effect estimators, generalizing results from the standard i. Wetzel, X. The authors explore an alternative way to model population ability distributions in large-scale educational surveys, where a latent regression model is often used to compensate for the shortage of cognitive information.
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In this article, the authors introduce an alternative approach to identify multiple groups that can account for the variation among students — conduct a Latent Class Analysis LCA. Bayesian Networks in Educational Research R. Almond, R. Mislevy, L. Steinberg, D. Williamson Statistics for Social and Behavioral Sciences. The authors explain and illustrate how Bayesian Networks, which combine statistical methods and computer-based expert systems, can be used to develop models for educational assessment.
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Haberman, L. The authors develop new methods to evaluate performance of test takers when items are scored both by human raters and by computers. The authors describe two alternative statistical approaches for estimating student growth percentiles SGP. The first estimates percentile ranks of current test scores conditional on past test scores directly. The second estimates SGP directly from longitudinal item-level data. Bertling, S. Stephenson, Y. Jia, R. Mislevy, M. Loh, Y. Liu, A. The authors discuss preliminary results from a project developed for assessing the collaborative problem-solving using web-based simulation.
Two participants collaborated via a chat box in this experiment in order to complete a science task. Bergner, D. The article discusses methodological challenges and problems with missing data that researchers face when seeking to understand the diverse group of students that take massively open online courses MOOCs. Solving these challenges is important to policymakers and providers of education. Bergner, K. Missing data and multiple attempts to answers by a user presents two challenges to scoring massively open online courses MOOCs.
The authors discuss these challenges in regards to ability estimation of homework items in a large-enrollment electrical engineering MOOC. The paper applies techniques from social network analysis to eye movement patterns in mathematics problem-solving. The authors construct and visualize transition networks using eye-tracking data collected from 37 8th grade students while solving linear function problems.
Lu, S. Haberman, H. The authors evaluate the impact of anchor selection on equating stability, which can strongly influence equating results in the real world, even when large examinee samples are present. This can provide a major hazard to the practical use of equating.
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Yao Journal of Educational Measurement , Vol. It suggests principles for exploring how various assessments relate to each other. Augmentation approaches developed for individual tests are applied to provide an accurate evaluation of combined assessments. The proposed methodology can be applied to other situations involving multiple assessments. Pseudo-Equivalent Groups and Linking S. The author explores an approach to linking test forms in the case of a nonequivalent groups design with no satisfactory common items.
He compares the reasonableness of results from pseudo-equivalent groups to results from kernel equating. Hao, Z. The authors examine the premise that gamification promotes motivation and engagement and therefore supports the learning process. The authors examined the effects of points, which is a basic element of gamification, on performance in a computerized assessment of mastery and fluency of basic mathematics concepts. Bennett Review of Research in Education , Vol. The article proceeds to explore and discuss in-depth the emerging third stage of assessments.
Kim, T. Yoo Journal of Educational Measurement , Vol. The authors discuss a potential bias due to measurement errors. This bias can affect student growth percentiles SGPs for individual students as well as mean or median SGPs on the aggregate level. The authors discuss various techniques that seek to decrease this bias. Jia Large-scale Assessments in Education , Vol. Bauer et. This paper describes the formative assessment value of simulation games, as seen in the work to develop "SimCityEDU: Pollution Challenge! Livingston ETS published book.
A nonmathematical introduction to equating, emphasizing conceptual understanding and practical applications. This is the second edition, which also covers raw and scaled scores, linear and equipercentile equating, data collection designs for equating, selection of anchor items, equating constructed-response tests and other tests that include constructed-response questions , and methods of anchor equating.
The authors investigate the creation of comparable score scales across countries in international assessments and examine potential improvements to current score scale calibration procedures used in international large-scale assessments. Rutkowski, M. Rutkowski eds. This handbook provides a broad guide to international large-scale assessments, behavioral statistics and policy. The handbook is of value to graduate students and researchers, as well as policy analysts familiar with quantitative methods without being expert in the field. Yan, A.