I have a specific problem concerning the prediction of how many goals TEAM A will score in a soccer match against TEAM B.
Ive decided which variables I want to use, but Im struggling to figure out exactly how to use them...
I am comparing TEAM A's attack with TEAM B's defence rather than the team's overall strengths.
For the entire previous soccer season, where every team played each other twice, I have:
AGS - Average goals scored per team per game
AGC - Average goals conceded per team per game
OAGSC - Average goals scored/conceded in all games
%FTS - % of games a team fails to score a goal
%CS - % of games a team doesn't concede a goal (Clean Sheet)
My original formula was:
PREDICTED TEAM A GOALS vs TEAM B = (AGS TEAM A + AGC TEAM B)/2
However I feel this is too simplistic so I created Overall Average Goals Scored per match and Overall Average Goals Conceded per match - which are of course the same, in order to compare the team's attacking and defensive strength with the average.
OAGSC is 1.32
TEAM A AGS is 2.11
TEAM B AGC is 1.05
So TEAM A scores an average 0.79 (=2.11 - 1.32) goals per game above the league average but TEAM B concedes 0.27 (=1.32 - 1.05) goals per game below the average.
Therefore TEAM A has a significantly more effective attack than the league average while TEAM B has a slightly better defence than the league average.
I feel that this means while TEAM A would normally score 2.11 goals against an average defence, they might score less because TEAM B has a slightly better than average defence. However, TEAM B would normally concede 1.05 goals to an average attack but TEAM A has a significantly stronger than average attack so TEAM B should concede more than their average/game.
Q1) How to I incorporate this into my formula and get a more accurate prediction for TEAM A goals scored in the match vs TEAM B?
I also have figures, as stated at the beginning, telling me how often TEAM failed to score and how often TEAM didnt concede.
TEAM A %FTS = 7.9% of games they played (3 of 38 matches)
TEAM B %CS = 42.1% of games they played (16 of 38 matches)
So TEAM A score at least 1 goal in 92.1% of their matches but TEAM B also manage not to concede in 42.1% of their matches (almost half!)
My instinct is to use these figures to create a second prediction, perhaps % chance that TEAM A wont score. Again I would like to weight this using the league averages as above, to recognise the relative strength of the attack and defence.
League Average %FTS and %CS is also of course the same and is 28.7% - i.e. 28.7% of the time a team in this league fails to score or doesnt concede.
Q2) How do I use these percentages to create a prediction of TEAM A failing to score? Should I combine all variables somehow or keep them as two seperate predictions?
Thanks in advance.