Intraclass Correlation Values for Planning Cluster Randomized Trials for English Learners
Angela Johnson, Melissa Arellanes, Benjamin West, Eric Larsen
Educators and policymakers need evidence from rigorous research studies to identify effective programs and strategies for teaching and supporting English Learners (ELs). Intervention research with ELs has frequently used cluster assignment designs. Two particularly important design parameters—intraclass correlation (ICC) and R-squared—play a key role in estimating the required sample size and power of cluster design studies. Design parameters for U.S. students in general have been available for nearly two decades, and researchers rely heavily on these estimates for design assumptions. To examine program impact for different populations, studies need to have sufficient power for each population. Currently, there is limited guidance on design parameters specific to ELs.
This study estimates research design parameters for ELs using longitudinal data from multiple states. The results will help researchers calculate sample sizes and plan rigorous intervention studies to evaluate the impact of programs and policies on ELs. This study can help ensure that planned evaluations of school- and district-level interventions have sufficient statistical power to estimate reasonable and educationally meaningful effect sizes for ELs. Estimating EL-specific design parameters contributes to centering research practices on ELs rather than the English-monolingual majority, elevating ELs’ representation in high-quality, rigorous research.
AVID Excel and Academic Outcomes for Long-Term English Learners
Angela Johnson & Diana Mercado-Garcia
Students who are still developing English proficiency after five to seven years in the US K-12 education system are labeled as long-term English Learners (LTELs). Despite policy priorities on addressing LTELs’ academic progress, very few studies have focused on programs targeting this student population. AVID Excel is a program designed for middle school LTELs and aims to improve their English proficiency and college and career readiness. This paper builds on a pilot survey study conducted in 2018 and estimates the association between participation in AVID Excel and students’ English proficiency and English reading test scores.