1. P.J. Heath, FFARCS, Senior Registrar, Anaesthetic Department, Southampton General Hospital, Southampton SO9 4XY.
2. T.W. Ogg, MA, FFARCS, Consultant and Director, Day Case Surgical Unit, Addenbrooke's Hospital, Cambridge CB2 2QQ.
3. W.R. Gilks, MSc, PhD. Statistician, Medical Research Council, Biostatistics Unit, Cambridge CB2 2BW.