Please use this identifier to cite or link to this item: http://hdl.handle.net/10419/119557
Authors: 
McConnell, Brendon
Vera-Hernández, Marcos
Year of Publication: 
2015
Series/Report no.: 
IFS Working Papers W15/17
Abstract: 
Basic methods to compute the required sample size are well understood and supported by widely available software. However, the sophistication of the sample size methods commonly used has not kept pace with the complexity of the experimental designs most often employed in practice. In this paper, we compile available methods for sample size calculations for continuous and binary outcomes with and without covariates, for both clustered and non-clustered RCTs. Formulae for panel data and for unbalanced designs (where there are different numbers of treatment and control observations) are also provided. The paper includes three extensions: (1) methods to optimize the sample when costs constraints are binding; (2) simulation methods to compute the power of a complex design; and (3) methods to consider in the sample size calculation adjustments for multiple testing. The paper is provided together with spreadsheets and STATA code to implement the methods discussed.
Subjects: 
Power analysis
Sample size calculations
Randomised Control Trials
Cluster Randomised Control Trial
Covariates
Cost Minimisation
Multiple outcomes
Simulation
JEL: 
C8
C9
Persistent Identifier of the first edition: 
Document Type: 
Working Paper

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