DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial di Cook, J, Julious, S, Sones, W, Hampson, L, Hewitt, C, Berlin, J, Ashby, D, Emsley, R, Fergusson, D, Walters, S, Wilson, E, Maclennan, G, Stallard, N, Rothwell, J, Bland, M, Brown, L, Ramsay, C, Cook, A, Armstrong, D, Altman, D, Vale, L

DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial di Cook, J, Julious, SA, Sones, WR, 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