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ERIC Number: EJ1034857
Record Type: Journal
Publication Date: 2013-Dec
Pages: 45
Abstractor: As Provided
ISSN: ISSN-0193-841X
Intraclass Correlations and Covariate Outcome Correlations for Planning Two-and Three-Level Cluster-Randomized Experiments in Education
Hedges, Larry V.; Hedberg, E. C.
Evaluation Review, v37 n6 p445-489 Dec 2013
Background: Cluster-randomized experiments that assign intact groups such as schools or school districts to treatment conditions are increasingly common in educational research. Such experiments are inherently multilevel designs whose sensitivity (statistical power and precision of estimates) depends on the variance decomposition across levels. This variance decomposition is usually summarized by the intraclass correlation (ICC) structure and, if covariates are used, the effectiveness of the covariates in explaining variation at each level of the design. Objectives: This article provides a compilation of school- and district-level ICC values of academic achievement and related covariate effectiveness based on state longitudinal data systems. These values are designed to be used for planning group-randomized experiments in education. The use of these values to compute statistical power and plan two- and three-level group-randomized experiments is illustrated. Research Design: We fit several hierarchical linear models to state data by grade and subject to estimate ICCs and covariate effectiveness. The total sample size is over 4.8 million students. We then compare our average of state estimates with the national work by Hedges and Hedberg.
SAGE Publications. 2455 Teller Road, Thousand Oaks, CA 91320. Tel: 800-818-7243; Tel: 805-499-9774; Fax: 800-583-2665; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Research
Education Level: Elementary Education; Secondary Education; Grade 1; Primary Education; Early Childhood Education; Grade 2; Grade 3; Grade 4; Intermediate Grades; Grade 5; Middle Schools; Grade 6; Grade 7; Junior High Schools; Grade 8; Grade 9; High Schools; Grade 10; Grade 11
Audience: N/A
Language: English
Sponsor: Institute of Education Sciences (ED)
Authoring Institution: N/A
Identifiers - Location: Arizona; Arkansas; Colorado; Florida; Kansas; Kentucky; Louisiana; Massachusetts; North Carolina; West Virginia; Wisconsin
Identifiers - Assessments and Surveys: Florida Comprehensive Assessment Test; Massachusetts Comprehensive Assessment System; Wisconsin Knowledge and Concepts Examinations
IES Funded: Yes
Grant or Contract Numbers: R305D110032