TY  - RPRT
        AU  - Konstantopoulos, Spyros
        TI  - The Power of the Test in Three-Level Designs
        PY  - 2006/Oct/
        PB  - Institute of Labor Economics (IZA)
        CY  - Bonn
        T2  - IZA Discussion Paper
        IS  - 2412
        UR  - https://www.iza.org/index.php/publications/dp2412
        AB  - Field experiments that involve nested structures may assign treatment conditions either to entire groups (such as classrooms or schools), or individuals within groups (such as students). Since field experiments involve clustering, key aspects of their design include knowledge of the intraclass correlation structure and the sample sizes necessary to achieve adequate power to detect the treatment effect. This study provides methods for computing power in three-level designs, where for example, students are nested within classrooms and classrooms are nested within schools. The power computations take into account clustering effects at the classroom and at the school level, sample size effects (e.g., number of students, classrooms, and schools), and covariate effects (e.g., pre-treatment measures). The methods are generalizable to quasi-experimental studies that examine group differences in an outcome, or associations between predictors and outcomes.
        KW  - experiments
KW  - clustering
KW  - nested designs
KW  - statistical power
KW  - randomized trials
KW  - treatment effects
KW  - random effects
        ER  -