Key points are not available for this paper at this time.
Stuart J. Pocock, Statistical Aspects of Clinical Trial Design, Journal of the Royal Statistical Society. Series D (The Statistician), Vol. 31, No. 1, Proceedings of the 1981 I.O.S. Annual Conference on Statistics in Medicine (Mar., 1982), pp. 1-18
Stuart Pocock (Mon,) studied this question.