Dear list, I'd like to test the null hypothesis of independence in a 2*2 contingency table in a Bayesian way. As far as I can see, this can be done by the function ctable in library LearnBayes. (More precisely, a Bayes factor can be computed.) Two questions: 1) Is there any other package/function than can be used for this in a more or less straightforward manner? 2) The ctable help page explains the parameter a as "a: matrix of prior hyperparameters", but it is not explained what the prior is and how it precisely depends on these hyperparameters. (I read the paper test_of_independence.pdf by the package author J. Albert on the web, but it only explains the choice a=1+0*data, but not general a.) Thank you, Christian *** --- *** Christian Hennig University College London, Department of Statistical Science Gower St., London WC1E 6BT, phone +44 207 679 1698 chrish at stats.ucl.ac.uk, www.homepages.ucl.ac.uk/~ucakche