Sample size calculations for evaluating treatment policies in multi-stage designs.

Clinical Trials : Journal of the Society for Clinical Trials
Ree Dawson, Philip W Lavori

Abstract

Sequential multiple assignment randomized (SMAR) designs are used to evaluate treatment policies, also known as adaptive treatment strategies (ATS). The determination of SMAR sample sizes is challenging because of the sequential and adaptive nature of ATS, and the multi-stage randomized assignment used to evaluate them. We derive sample size formulae appropriate for the nested structure of successive SMAR randomizations. This nesting gives rise to ATS that have overlapping data, and hence between-strategy covariance. We focus on the case when covariance is substantial enough to reduce sample size through improved inferential efficiency. Our design calculations draw upon two distinct methodologies for SMAR trials, using the equality of the optimal semi-parametric and Bayesian predictive estimators of standard error. This 'hybrid' approach produces a generalization of the t-test power calculation that is carried out in terms of effect size and regression quantities familiar to the trialist. Simulation studies support the reasonableness of underlying assumptions as well as the adequacy of the approximation to between-strategy covariance when it is substantial. Investigation of the sensitivity of formulae to misspecification shows ...Continue Reading

References

May 3, 2000·Statistics in Medicine·P F ThallH G Sung
Nov 12, 2005·Clinical Trials : Journal of the Society for Clinical Trials·Philip W Lavori, Ree Dawson
Apr 12, 2007·Biometrics·Yuliya Lokhnygina, Jeffrey D Helterbrand
Sep 13, 2007·Clinical Trials : Journal of the Society for Clinical Trials·Philip W Lavori, Ree Dawson
Oct 5, 2007·Statistics in Medicine·Ree Dawson, Philip W Lavori
Oct 5, 2007·Annual Review of Medicine·Philip W Lavori, Ree Dawson
Jun 24, 2008·Statistics in Medicine·Marcel Wolbers, Jeffrey D Helterbrand
Apr 22, 2009·Statistics in Medicine·Wentao Feng, Abdus S Wahed
Dec 1, 2001·Journal of the American Statistical Association·S A MurphyUNKNOWN CPPRG

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Citations

Nov 28, 2012·Biostatistics·Kelley M Kidwell, Abdus S Wahed
Nov 18, 2014·Annual Review of Statistics and Its Application·Bibhas Chakraborty, Susan A Murphy
Sep 27, 2016·Progress in Biophysics and Molecular Biology·C O S SorzanoJ M Carazo
Apr 16, 2014·Clinical Trials : Journal of the Society for Clinical Trials·Kelley M Kidwell
Jun 14, 2014·Clinical Trials : Journal of the Society for Clinical Trials·Bibhas ChakrabortyYing-Qi Zhao
Sep 29, 2015·Statistics in Medicine·Semhar B OgbagaberAbdus S Wahed

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