Possible Bug: Negative Numbers on Output

[swallace21]

If I switch the last match-up to barcelona beating man utd I get negative numbers: man utd :: -0.363 psg :: -0.375 ac milan :: -0.394 barcelona :: -0.439

matches = [('barcelona', 'man utd'), ('man utd', 'ac milan'), ('barcelona', 'ac milan'), ('ac milan', 'psg'), ('psg', 'man utd'), ('barcelona', 'psg'), ('barcelona', 'man utd')]