Over some time I have tried out an over/under system that is just based on statistics from a league in one season. I wanted to see how I would do against the bookies by using the following method:
For every round I would first find the average amount of goals scored in the league, I would then divide that number by 2 so that I would get a base value for each of the teams. EX. 2,5 goals scored on average=base value 1,225 per team.
For the home team I would use the following criteria to find out how many goals they would score: (home goals scored/home games played)-base value per team. EX. Home team scored 30 goals in 15 matched, so 30/15-1,225=0,625. So by this I figure that the hometeam will score on average 0,625 goals more than average. 1,225+0,625=1,85 goals
I then do the same with the away team. (Away goals scored/awaygames
played)-base value. EX. 14 goals scored/ 15 games
I figure that the away team will score 0,292 goals less than average.
I now have an estimated value of how many goals there will be in this match by adding the expected home goals and expected away goals.
In the long term I expect this value to be going closer to the league average so I add the league average 2,5 with the expected goals from the match 2,783 and divide by 2. EX. (2,5+2,783)/2=2,6415
In this this match I expect there will be scored 2,6415 goals. I then use a poisson calculation to estimate how often there will be scored 0, 1 or 2 goals when the average is 2,6415 and find that it will be a under 50,8% of the times.
I then set the right odds for Under/Over to be 1/0,508=1,9685 and 1/0,492=2,0325
If a bookie is now giving odds that are higher than that for under/over I will then take that odds.