The distribution of p-values under the null hypothesis is well-known to be U(0,1). This distribution under the alternative hypothesis has been discussed by a number of people at various times*. I seem to recall that Birnbaum was an early example. a) does anybody have an exact reference to Birnbaum's paper? b) does anyone have an earlier reference? Many thanks Stephen Senn *e.g Miettinen, Theoretical Epidemiology, Senn, Controlled Clinical Trials 1993, Hwang, O'Neill & Bauer, Stats in Medicine, 1998 Professor Stephen Senn Department of Statistical Science & Department of Epidemiology and Public Health University College London Room 126, 1-19 Torrington Place LONDON WC1E 6BT Tel: +44 (0) 20 7679 1698 Fax: +44 (0) 20 7383 4703 Email: [log in to unmask] webpage: http://www.ucl.ac.uk/~ucaksjs/ ------------------------------------------------- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%