How do I calculate the probability of an event in betting?
Whereas in casinos, such as roulette, the probability of a particular result is always known, in sports betting it is never possible to calculate the exact probability. And, in fact, that is the reason why betting differs favorably from casinos. It is always possible to find bets, the probability of which is higher than the one set by the bookmaker Рarimatch bet. So how to do it?
There is no developed method for calculating probability that can determine the odds as accurately as possible. This is impossible because of the influence of many factors on the result, the unpredictability of sports in general. For example, a program or formula where one could enter the data and get an approximate result. However, there is a known algorithm for determining the probability of the outcome. Let's consider its stages.
The first stage is the study of statistics.
Statistics itself does not allow you to get even an approximate probability. It is wrong to think that if in the previous 10 games the team 3 times played in a draw, the probability of a draw in the next match will be 30%. Recall the theory of probability, which states that previous events do not affect the probability of future events. But statistics serves as a starting point, a baseline, because we need something to build upon.
The second step is the influence of factors
After defining the initial probability with the help of statistics, the match should be analyzed taking into account as many factors as possible. Consequently, after studying the influence of each of them, corrections are made to the calculated probabilities.
It is at the second stage that everything depends on the player's knowledge of the sport he is betting on. As much as we would like to conceptualize and structure everything, it is impossible to calculate the exact odds and determine how this or that factor influences the probability. Each sporting event requires a case-by-case approach.
An example of determining the probability of outcomes in betting
Let us consolidate the material of the previous paragraph with an example. We will evaluate the match Arsenal - Liverpool, let's study the main line. The odds are as follows: Arsenal win - 2.25, draw - 3.80, Liverpool win - 3.05. Let's convert the quotations into probability. And we get the following: N1 - 44.44%, X - 26.31%, N2 - 32.78%.
Now let's calculate the probability and compare with the bookmaker's odds and define the gross, if any. Let's note right away that all statistical data and factors are conditional.
To begin with, let's study the statistics
Arsenal had 8 wins and 2 draws in the last 10 home matches. We get 80% - 20% - 0%. Liverpool in the last 10 away games had 6 wins, 2 draws and 2 losses. So we have 20% - 20% - 60%. Calculate the average: 50% - 20% - 30%.
After that, we go to the second step - accounting for various factors. First of all, we look at injuries and disqualifications. The guests have practically no losses, while the home team has lost its central defender and left winger because of injuries. Adjusting the probabilities after receiving this information: 46% - 22% - 32%.
Also in the pre-match analysis we find out that Liverpool had two more days rest, while Arsenal had their previous match three days ago. Fatigue could have an impact. Change the odds: 44% - 23% - 33%.
Let's look at the face-to-face meetings between the teams
In the last five games Liverpool has two wins and three draws. Of course, the chances of Arsenal are noticeably decreasing. We get approximately: 40% - 25% - 35%. Other significant factors are not identified, so we conclude the analysis.
The final result is 40% - 25% - 35%, and the bookmaker probabilities of P1 - 44.44%, X - 26.31%, P2 - 32.78%. Thus, the bet on Liverpool's victory is valuable - the real probability is 35% and the odds are 32.78%.