Planning longitudinal studies can be challenging as various design decisions need to be made. Often, researchers are in search for the optimal design that maximizes statistical power to test certain parameters of the employed model. We provide a user-friendly Shiny app OptDynMo available at https://shiny.psychologie.hu-berlin.de/optdynmo that…

Cluster randomized control trials often incorporate a longitudinal component where, for example, students are followed over time and student outcomes are measured repeatedly. Besides examining how intervention effects induce changes in outcomes, researchers are sometimes also interested in exploring whether intervention effects on outcomes are…

This article develops new closed-form variance expressions for power analyses for commonly used difference-in-differences (DID) and comparative interrupted time series (CITS) panel data estimators. The main contribution is to incorporate variation in treatment timing into the analysis. The power formulas also account for other key design features…

Single subject (SS) designs are popular in educational and psychological research. There exist several statistical techniques designed to analyze such data and to address the question of whether an intervention has the desired impact. Recently, researchers have suggested that generalized additive models (GAMs) might be useful for modeling…

The authors compared the effects of using the true Multilevel Latent Growth Curve Model (MLGCM) with single-level regular and design-based Latent Growth Curve Models (LGCM) with or without the higher-level predictor on various criterion variables for multilevel longitudinal data. They found that random effect estimates were biased when the…

PCI Education conducted a three-year longitudinal study to determine the comparative effectiveness of the "PCI Reading Program" ("PCI") for students with severe disabilities as implemented in Florida's Brevard Public Schools and Miami-Dade County Public Schools. The primary question addressed by the study is whether students…

PCI Education sought scientifically based evidence on the effectiveness of the "PCI Reading Program--Level One" for students with severe disabilities. During the 2007-2008 academic year. Empirical Education conducted a randomized control trial (RCT) in two Florida districts, Brevard and Miami-Dade County Public Schools. For this…

Documents the methodology of the second follow-up interview of the Baccalaureate and Beyond Longitudinal Study, describing sample design, instruction development and data collection, response rates, efficacy of the survey instrument, and weights and design effects. (Author/SLD)

This report develops the sample design for evaluating five Federal manpower programs in terms of their effects upon trainees' incomes. The study involves a large 10-city sample of trainees in Job Corps, Neighborhood Youth Corps, Job Opportunities in the Business Sector, and Manpower and Development Act Institutional Training Programs (New Careers…

Simple methods for detecting attrition (nonresponse) in longitudinal evaluations are reviewed, focusing on regression-based analyses of data from a longitudinal evaluation. The approaches are illustrated with data from the Fort Bragg Evaluation, an evaluation of a major demonstration in children's mental health services. (SLD)

This study by two Ph.D. students in library science reviewed a systematic sample of the research literature in library and information science published in 62 core library journals in 1983 to order to identify substantive articles and compare their findings on research methodologies and trends with those reported in a similar study performed in…

Appendix A, "Data Analysis When Students Change from Smaller to Larger Schools between the Pre-test and Post-test of the First Year," discusses a methodological problem involved in planning the approximate number of questionnaires to be administered in program. Appendix B, "Estimates of Sample Sizes and Data Collection Costs," includes five…

The sampling of teachers for nationwide surveys offers a challenging endeavor in obtaining a representative and adequate sample to truly represent opinions of the teachers. Ten national surveys of public school teachers conducted between 1980 and 1985 are presented with respect to their sampling design and procedures. Concepts and theoretical…

An efficiency study was conducted of the base year design used for the National Longitudinal Study of the High School Class of 1972 (NLS). Finding the optimal design involved a search for the numbers of sample schools and students that would maximize the variance at a given cost. Twenty-one variables describing students' plans, attitudes,…

An efficiency study was conducted of the sampling design used for the National Longitudinal Study of the High School Class of 1972 (NLS), and the change variables used in the first followup. Nine alternative designs were compared, using a cost model based upon the number of schools and students sampled. Fourteen change variables and eight domains…