?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.aulast=Cook&rft.au=Cook%2C+JA&rft.aufirst=JA&rft.atitle=DELTA(2)+guidance+on+choosing+the+target+difference+and+undertaking+and+reporting+the+sample+size+calculation+for+a+randomised+controlled+trial&rft.volume=19&rft.date=5+November+2018&rft.issn=1745-6215&rft.title=Trials&rft.genre=article