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ERIC Number: ED510553
Record Type: Non-Journal
Publication Date: 2010-May
Pages: 74
Abstractor: As Provided
Reference Count: 8
New Estimates of Design Parameters for Clustered Randomization Studies: Findings from North Carolina and Florida. Working Paper 43
Xu, Zeyu; Nichols, Austin
National Center for Analysis of Longitudinal Data in Education Research
The gold standard in making causal inference on program effects is a randomized trial. Most randomization designs in education randomize classrooms or schools rather than individual students. Such "clustered randomization" designs have one principal drawback: They tend to have limited statistical power or precision. This study aims to provide empirical information needed to design adequately powered studies that randomize schools using data from Florida and North Carolina. The authors assess how different covariates contribute to improving the statistical power of a randomization design and examine differences between math and reading tests; differences between test types (curriculum-referenced tests versus norm-referenced tests); and differences between elementary school and secondary school, to see if the test subject, test type, or grade level makes a large difference in the crucial design parameters. Finally they assess bias in 2-level models that ignore the clustering of students in classrooms. (Contains 5 figures, 46 tables and 2 footnotes.)
National Center for Analysis of Longitudinal Data in Education Research. The Urban Institute, 2100 M Street NW, Washington, DC 20037. Tel: 202-261-5739; Fax: 202-833-2477; e-mail:; Web site:
Publication Type: Numerical/Quantitative Data; Reports - Evaluative
Education Level: Elementary Education; Elementary Secondary Education; Secondary Education
Audience: N/A
Language: English
Sponsor: William T. Grant Foundation
Authoring Institution: Urban Institute, National Center for Analysis of Longitudinal Data in Education Research (CALDER)
Identifiers - Location: Florida; North Carolina
Identifiers - Assessments and Surveys: Florida Comprehensive Assessment Test; North Carolina End of Course Testing Program
IES Funded: Yes
Grant or Contract Numbers: R305A060067