Cook, JA; Julious, SA; Sones, W; Hampson, LV; Hewitt, C; Berlin, JA; Ashby, D; ... Vale, LD; + view all 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; - view fewer (2018) DELTA(2) guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial. Trials , 19 , Article 606. 10.1186/s13063-018-2884-0.