Thanks Vasco, and you are right. How Elo and related systems ‘manage’ draws/​partial credit is something I didn’t explore, but as you say the commonest approach is to set ‘draw’ at 0.5. The equation above is still true for games which only have wins or losses (so P(A draws) = 0).
Thanks Vasco, and you are right. How Elo and related systems ‘manage’ draws/​partial credit is something I didn’t explore, but as you say the commonest approach is to set ‘draw’ at 0.5. The equation above is still true for games which only have wins or losses (so P(A draws) = 0).