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FULL GUIDANCE

The DELTA2 guidance is available as a preprint:

Cook JA, Julious SA, Sones W, Hampson LV, Hewitt C, Berlin JA, Ashby D, Emsley R, Fergusson DA, Walters SJ, Wilson EC, Maclennan G, Stallard N, Rothwell JC, Bland M, Brown L, Ramsay CR, Cook A, Armstrong D, Altman D, Vale LD. Choosing the target difference ("effect size") for a randomised controlled trial - DELTA2 guidance. Preprints 2018, 2018080521. https://doi.org/10.20944/preprints201808.0521.v1.

The final DELTA2 guidance is anticipated to be published in the NIHR Health Technology Assessment Journal in early 2019.

SUMMARY GUIDANCE

A summary of the DELTA2 guidance is freely available in the BMJ and Trials:

Cook JA, Julious SA, Sones W, Hampson LV, Hewitt C, Berlin JA, Ashby D,  Emsley R, Fergusson DA, Walters SJ, Wilson ECF, MacLennan G, Stallard N, Rothwell JC, Bland M, Brown L, Ramsay CR, Cook A, Armstrong D, Altman D, Vale LD. DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial. BMJ 2018; 363. https://doi.org/10.1136/bmj.k3750    

Cook JA, Julious SA, Sones W, Hampson LV, Hewitt C, Berlin JA, Ashby D,  Emsley R, Fergusson DA, Walters SJ, Wilson ECF, MacLennan G, Stallard N, Rothwell JC, Bland M, Brown L, Ramsay CR, Cook A, Armstrong D, Altman D, Vale LD. DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial. Trials 2018; 19: 606. https://doi.org/10.1186/s13063-018-2884-0

 

RELATED ARTICLE COLLECTION

An article collection of all DELTA2-related papers is available in Trials:

Protocol

The DELTA2 protocol has been published and is freely available:

Cook JA, Julious SA, Sones W, Rothwell JC, Ramsay CR, Hampson LV, Emsley R, Walters SJ, Hewitt C, Bland MJ, Fergusson DA, Berlin J, Altman D, Vale LD. Choosing the target difference ("effect size") for a randomised controlled trial - DELTA2 guidance protocol. Trials. 2017; 18: 271. https://doi.org/10.1186/s13063-017-1969-5

Development

A paper on the development of the DELTA2 guidance and related findings is freely available in Trials:

Sones W, Julious SA, Rothwell JC, Ramsay CR, Hampson LV, Emsley R, Walters SJ, Hewitt C, Bland M, Fergusson DA, Berlin JA, Altman D, Vale LD, Cook JA. Choosing the target difference ("effect size") for a randomised controlled trial - the development of the DELTA2 guidance. Trials 2018; 19: 542. https://doi.org/10.1186/s13063-018-2887-x

Commentary

Bell M. New guidance to improve sample size calculations for trials: eliciting the target difference. Trials 2018; 19: 605. https://doi.org/10.1186/s13063-018-2894-y

Review

A review of the target differences in clinical trials published in the Health Technology Assessment journal:

Rothwell J, Julious SA, Cooper CL. A study of target effect sizes in randomised controlled trials published in the Health Technology Assessment journal. Trials 2018; 19: 544. https://doi.org/10.1186/s13063-018-2886-y   

DELTA guidance

Preceding the DELTA2 project, the DELTA project published guidance on specifying the target difference in the primary outcome of a randomised controlled trial:

Cook JA, Hislop J, Altman DG, Fayers PM, Briggs AH, Ramsay CR, Norrie JD, Harvey IM, Buckley B, Fergusson D, Ford I, Vale LD. Specifying the target difference in the primary outcome for a randomised controlled trial: guidance for researchers. Trials 2015; 16: 12 https://doi.org/10.1186/s13063-014-0526-8   

 

RELATED ONLINE PUBLICATIONS

Getting sample size right for clinical trials (news article). NDORMS departmental website; 6 November 2018.

Improving sample size calculation and reporting for randomized trials with DELTA2 guidance (blog post). BMC Blog Network: On Medicine; 6 November 2018.