Risk of selection bias in randomized trials: further insightReport as inadecuate

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, 17:485

First Online: 07 October 2016Received: 17 September 2015Accepted: 11 September 2016DOI: 10.1186-s13063-016-1597-5

Cite this article as: Berger, V.W. Trials 2016 17: 485. doi:10.1186-s13063-016-1597-5


The quality of randomization is an under-appreciated facet of trial design. The present piece represents an advance in our collective understanding of how allocation concealment and randomization relate to risk of selection bias in randomized trials, and other measures are also considered. Though the overwhelming majority of the advice given is timely and correct, it is more instructive to focus on the relatively narrow sliver of advice that is incorrect namely, that trials should not stratify by site, and that unrestricted randomization is a solution to the problem of selection bias, so it is in this context that the comments here must be understood. In no way is this intended to be a rebuttal of the excellent work we have before us. Rather, it is a refinement.

KeywordsAllocation concealment Berger-Exner test Conditional unrestricted randomization Maximal procedure AbbreviationsMTIMaximally tolerated imbalance


PPPrescribing physician


Author: Vance W. Berger

Source: https://link.springer.com/

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