DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial.
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.