Just as the name implies, Goal Expectancy simply refers to the number of goals a team is expected to score. This is after checking a teams potential to score, concede and the ability of their opponents to do same. This articles main aim would be to show how we go about calculating these.
This subject is associated with so much excitement over the years. Punters and academicians alike have their own views on the topic. It is also important that we take note of the accuracy of our goal expectancy survey in any given match. As this would lead to a corresponding consistency in our resolve to find value bets and make profits often.
In football betting in general, profitability is dependent on the ability of any strategy/system/model to accurately predict outcomes. And also a translating its forecast to value bets. This is where we have to introduce Poisson Distribution.
Poisson distribution
This statistical variable refers to the calculation that provides the probability of every possible scoreline in an upcoming football match. The goal expectancy value is put into consideration when trying to attain this.
Poisson distribution is a very complex subject, but there no need to know the entirety of it. This is because Microsoft Excel comes with an inbuilt Poisson function.
Calculation
In mathematical terms, the formula to apply on Excel to derive Poisson is:
=POISSON(x, mean, cumulative)
Mean refers to the goal expectancy for each team. The Cumulative would be at FALSE, so as to get a Poisson value that would be a random variable. The random variable used here is the goal.
lets speak English
If we are looking at the probability of a team scoring three times in a particular match, and the goal expectancy is 3.1 goals. Here the formula would as;
=POISSON(3,3.1,FALSE)
This would be 0.223677 which also means there would be a 22.37% chance of this team to score exactly 3 goals.
In order to do this effectively, the probability for all the goals or the possible number of goals should be given.
The excel spreadsheet when further studied will help provide values for match result, draw no bet, over 2.5 goals and so on.
Disadvantage of the Poisson distribution
It is a general assumption that the goals are independent with no dependence on another goal. Football results in general
Are not supposed to be interpreted independently.
Secondly, the Poisson distribution underestimates the possibility of one team or both teams in a particular match not scoring a goal. Hence dismissing the likelihood of a match ending as a draw.
This article will help you in your bid to succeed in goal expectancy but there is still a lot more to learn. If you are really keen on this topic, do a little research on Poisson distribution. There are a lot of articles on the internet, to be able to broaden your knowledge you could read more on key topics that tickle your fancy.
In subsequent articles, we will broaden your knowledge on goal expectancy as we. Just touched the tip of the Iceberg with this post.
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