A process for determining relative player skills and draw margins is described. Information about an outcome of a game between at least a first player opposing a second player is received. Also, for each player, skill statistics are received associated with a distribution representing belief about skill of that player. Draw margin statistics are received associated with a distribution representing belief about ability of that player to force a draw. An update process is performed to update the statistics on the basis of the received information about the game outcome. In an embodiment a Bayesian inference process is used during the update process which may take past and future player achievement into account.