Statistical Science

Selecting a Biased-Coin Design

Anthony C. Atkinson

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Biased-coin designs are used in clinical trials to allocate treatments with some randomness while maintaining approximately equal allocation. More recent rules are compared with Efron’s [Biometrika 58 (1971) 403–417] biased-coin rule and extended to allow balance over covariates. The main properties are loss of information, due to imbalance, and selection bias. Theoretical results, mostly large sample, are assembled and assessed by small-sample simulations. The properties of the rules fall into three clear categories. A Bayesian rule is shown to have appealing properties; at the cost of slight imbalance, bias is virtually eliminated for large samples.

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Statist. Sci., Volume 29, Number 1 (2014), 144-163.

First available in Project Euclid: 9 May 2014

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Clinical trial covariate balancing loss of information optimum experimental design random allocation selection bias


Atkinson, Anthony C. Selecting a Biased-Coin Design. Statist. Sci. 29 (2014), no. 1, 144--163. doi:10.1214/13-STS449.

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