Correction to: Choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial - the development of the DELTA2 guidance.

Following publication of the original article [1], we have been notified of a few mistakes.

RCT Entities:   Population Interventions Outcomes

Correction to: Trials (2018) 19:542

https://doi.org/10.1186/s13063-018-2887-x

Following publication of the original article [1], we have been notified of a few mistakes:

Figure 1:

“1351 titles and abstracts” should read “1322 titles and abstracts”

"Stat Biopharm Res" value should be "8" instead of "18"

"Stat Med" value should be "226" instead of "74"

"Stat Methods Med Res" value should be "74" instead of "226"

Results section, Stage 5, first paragraph, the phrase:

“It was endorsed by the MRC-NIHR Methodology Advisory Group on March 12, 2018, with minor updating of references and the final version produced on April 18, 2017” should read

“It was endorsed by the MRC-NIHR Methodology Advisory Group on March 12, 2018, with minor updating of references and the final version produced on April 18, 2018”.