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Sample size calculations and specifying the target difference for randomized trials

An article collection published in Trials.

A key step in the design of a randomized controlled trial (RCT) is the estimation of the number of participants needed. Despite the critical role of the target difference in the primary outcome in a conventional RCT sample size, the manner in which it is determined, has received relatively little attention. Additionally, guidance on the reporting of the sample size calculation for a RCT is sorely needed. This article collection addresses these gaps in the literature. It includes a summary of the new DELTA2 guidance for researchers and funder representatives on the specification and reporting of the target difference and the sample size calculation for an RCT. Further articles address how the DELTA2 guidance was developed, previous guidance on this topic, along with a review of practice in a cohort of RCTs and a commentary on the value of the new guidance.

  1. Content type: Methodology

    A key step in the design of a RCT is the estimation of the number of participants needed in the study. The most common approach is to specify a target difference between the treatments for the primary outcome ...

    Authors: Jonathan A. Cook, Steven A. Julious, William Sones, Lisa V. Hampson, Catherine Hewitt, Jesse A. Berlin, Deborah Ashby, Richard Emsley, Dean A. Fergusson, Stephen J. Walters, Edward C. F. Wilson, Graeme Maclennan, Nigel Stallard, Joanne C. Rothwell, Martin Bland, Louise Brown…

    Citation: Trials 2018 19:606

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  2. Content type: Research

    A key step in the design of a randomised controlled trial is the estimation of the number of participants needed. The most common approach is to specify a target difference in the primary outcome between the r...

    Authors: William Sones, Steven A. Julious, Joanne C. Rothwell, Craig Robert Ramsay, Lisa V. Hampson, Richard Emsley, Stephen J. Walters, Catherine Hewitt, Martin Bland, Dean A. Fergusson, Jesse A. Berlin, Doug Altman, Luke David Vale and Jonathan Alistair Cook

    Citation: Trials 2018 19:542

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  3. Content type: Research

    When designing a randomised controlled trial (RCT), an important consideration is the sample size required. This is calculated from several components; one of which is the target difference. This study aims to...

    Authors: Joanne C. Rothwell, Steven A. Julious and Cindy L. Cooper

    Citation: Trials 2018 19:544

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  4. Content type: Study protocol

    A key step in the design of a randomised controlled trial (RCT) is the estimation of the number of participants needed. By far the most common approach is to specify a target difference and then estimate the c...

    Authors: Jonathan A. Cook, Steven A. Julious, William Sones, Joanne C. Rothwell, Craig R. Ramsay, Lisa V. Hampson, Richard Emsley, Stephen J. Walters, Catherine Hewitt, Martin Bland, Dean A. Fergusson, Jesse A. Berlin, Doug Altman and Luke D. Vale

    Citation: Trials 2017 18:271

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  5. Content type: Research

    Central to the design of a randomised controlled trial is the calculation of the number of participants needed. This is typically achieved by specifying a target difference and calculating the corresponding sa...

    Authors: Jonathan A Cook, Jenni Hislop, Douglas G Altman, Peter Fayers, Andrew H Briggs, Craig R Ramsay, John D Norrie, Ian M Harvey, Brian Buckley, Dean Fergusson, Ian Ford and Luke D Vale

    Citation: Trials 2015 16:12

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