The inverted index is the main data structure used by all the major search engines. Search engines build an inverted index on their collection to speed up query processing. As the size of the web grows, the length of the inverted list structures, which can easily grow to hundreds of MBs or even GBs for common terms (roughly linear in the size of…

This brief discusses the problem of scaling innovations in education in the United States so that they can serve very large numbers of students. It begins with a general discussion of the issues involved, develops a set of five criteria for assessing challenges of scaling, and then uses three programs widely discussed in the U.S. as examples of…

Over the last two decades, education privatization has become a widespread phenomenon, affecting most education systems and giving place to a consistent increase in private school enrolment globally. However, far from being a monolithic phenomenon, privatization advances through a variety of context-sensitive policy processes that translate into…

The conventional approach to scaling up educational reforms considers the development and testing phases to be distinct from the work of implementing at scale. Decades of research suggest that this approach yields inconsistent and often disappointing improvements for schools most in need. More recent scholarship on scaling school improvement…

The conventional approach to school implementation involves different sets of schools in designing, developing, and testing an innovation and yet another set of schools involved in implementation at scale. Decades of research suggest that this approach has yielded inconsistent and often disappointing improvements for schools most in need. More…

Higher education is deploying a range of innovative strategies in response to rising costs and financial challenges. This report presents findings from a NASPA [National Association of Student Personnel Administrators] study on cost-saving initiatives at three institutions. Each institution aimed to creatively address different areas affecting…

A weighted Euclidean distance model for analyzing three-way dissimilarity data (stimuli by stimuli by subjects) for heterogeneous subjects is proposed. First, it is shown that INDSCAL may fail to identify a common space representative of the observed data structure in presence of heterogeneity. A new model that removes the rotational invariance of…

This dissertation is comprised of three papers that propose and apply psychometric models to deal with complexities and challenges in large-scale assessments, focusing on modeling rater effects and complex learning progressions. In particular, three papers investigate extensions and applications of multilevel and multidimensional item response…

This study offers validity evidence for the Parental Academic Support Scale, a 16-item multidimensional measure that assesses support related to a child's academic performance, classroom behavior, preparation, hostile peer interactions, and health. Confirmatory factor analysis of the Parental Academic Support Scale (PASS) revealed a close model…

This paper argues for innovation diffusion as a "becoming" process in the context of lateral and vertical moves. The context of these innovations involves technology-mediated innovations and their diffusion trajectories in the Singapore education system. Embedded in a centralized-decentralized dialectics, this paper traces particular…

Similarity is a fundamental concept in the middle grades. In this study, we applied Vergnaud's theory of conceptual fields to answer the following questions: What concepts-in-action and theorems-in-action about similarity surfaced when students worked in a novel task that required them to enlarge a puzzle piece? How did students use geometric…

Item parameter drift (IPD) occurs when item parameter values change from their original value over time. IPD may pose a serious threat to the fairness and validity of test score interpretations, especially when the goal of the assessment is to measure growth or improvement. In this study, we examined the effect of multidirectional IPD (i.e., some…

The nonequivalent groups anchor test (NEAT) design is often used to scale item parameters from two different test forms. A subset of items, called the anchor items or common items, are administered as part of both test forms. These items are used to adjust the item calibrations for any differences in the ability distributions of the groups taking…

Lord and Wingersky's (1984) recursive algorithm for creating summed score based likelihoods and posteriors has a proven track record in unidimensional item response theory (IRT) applications. Extending the recursive algorithm to handle multidimensionality is relatively simple, especially with fixed quadrature because the recursions can be defined…

Passive, lecture-based forms of instruction are often ineffective in helping students develop deep conceptual understanding of scientific concepts. Student-centered forms of instruction based in a constructivist framework, where students are guided toward actively constructing their understanding, have been met with greater success. However,…