Assurance for clinical trial design with normally distributed outcomes: eliciting uncertainty about variances

2017/02/03 by Alhussain, Ziyad A., Oakley, Jeremy E.
#FOS: Computer and information sciences #Methodology (stat.ME)

paper · doi:10.48550/arxiv.1702.00978

Abstract

The assurance method is growing in popularity in clinical trial planning. The method involves eliciting a prior distribution for the treatment effect, and then calculating the probability that a proposed trial will produce a `successful' outcome. For normally distributed observations, uncertainty about the variance of the normal distribution also needs to be accounted for, but there is little guidance in the literature on how to elicit a distribution for a variance parameter. We present a simple elicitation method, and illustrate how the elicited distribution is incorporated within an assurance calculation. We also consider multi-stage trials, where a decision to proceed with a larger trial will follow from the outcome of a smaller trial; we illustrate the role of the elicted distribution in assessing the information provided by a proposed smaller trial. Free software is available for implementing our methods.

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