Title Linear Mixed-Effects Models using 'Eigen' and S4 Contact LME4 Authors Description Fit linear and generalized linear mixed-effects models. The models and their components are represented using S4 classes and methods. The core computational algorithms are implemented using the 'Eigen' C++ library for numerical linear algebra and 'RcppEigen' ``glue''. Depends R (>= 3.2.0), Matrix (>= 1.2-1), methods, stats LinkingTo Rcpp (>= 0.10.5), RcppEigen

Value-added models of student achievement have received widespread attention in light of the current test-based accountability movement. These models use longitudinal growth modeling techniques to identify effective schools or teachers based upon the results of changes in student achievement test scores. Given their increasing popularity, this article demonstrates how to perform the data analysis necessary to fit a general value-added model using the nlme package available for the R statistics environment. We demonstrate techniques for inspecting the data prior to fitting the model, walk a practitioner through a sample analysis, and discuss general extensions commonly found across the literature that may be incorporated to enhance the basic model presented, including the estimation of multiple outcomes and teacher effects.

The information function is an important statistic in item response theory (IRT) applications. Although the information function is often described as the IRT version of reliability, it differs from the classical notion of reliability from a critical perspective: replication. This article first explores the information function for the one-parameter model in detail and suggests an alternative method for its computation. Second, the difference between the IRT and classical test theory standard errors of measurement is discussed.

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The analysis of longitudinal data in education is becoming more prevalent given the nature of testing systems constructed for No Child Left Behind Act (NCLB). However, constructing the longitudinal data files remains a significant challenge. Students move into new schools, but in many cases the unique identifiers (ID) that should remain constant for each student change. As a result, different students frequently share the same ID, and merging records for an ID that is erroneously assigned to different students clearly becomes problematic. In small data sets, quality assurance of the merge can proceed through human reviews of the data to ensure all merged records are properly joined. However, in data sets with hundreds of thousands of cases, quality assurance via human review is impossible. While the record linkage literature has many applications in other disciplines, the educational measurement literature lacks details of formal protocols that can be used for quality assurance procedures for longitudinal data files. This article presents an empirical quality assurance procedure that may be used to verify the integrity of the merges performed for longitudinal analysis. We also discuss possible extensions that would permit merges to occur even when unique identifiers are not available.