2.2. The expert model
The expert BN (see Fig. 1) uses only a few features:
• The presence or absence of three players, Sherringham,
Anderton, and Armstrong. So in each match each of
these values was true or false.
• The playing position of Wilson represented by him playing
in midWeld or not.
• The quality of the opposing team. This particular variable
was measured on a simple 3-point scale (high,
medium, and low). Although based on expert judgement,
it matches closely with the teams’ Wnal league positions
(‘top 6’, ‘middle 8’, or ‘bottom 6’) and so would appear
to be an accurate reXection of their average performance.
• Venue (whether the game is played at Spurs’ home
ground or away).
The BN shows how the expert constructed the relationships
between the chosen factors and the outcome of the
game. In addition to the result node (win, lose, or draw) the
BN includes three other nodes to simplify the structure:
• Attack which represents the quality of the Spurs attacking
force (low, medium, and high).
• Spurs_quality the overall quality of the Spurs team (low,
medium, and high).
• Performance how well the team will perform given their
own quality and that of the opposition (low, medium,
and high).