Odds & Probability


Odds are referred to as “fair” if betting odds equal the true value of the odds. It looks simple but it is definitely more complex than an event like a coin flip, where you can calculate the chance of an outcome more easily. We all know that the probability of flipping a head occurring is 50% and also 50% for tails as there are only 2 outcomes. Let’s suppose the bookmaker offers 6/5 (2.2 in decimals) for heads. Based on mathematic calculation to find the probability, this is 1 / (decimal odd) * 100, which makes it 1 / 2.2 = 0.45 * 100 = 45%.
This is to say that the odds of 2.2 that were offered for heads represents a 45% chance of heads occurring even though we know that the true value of heads should be 50%, which is represented by evens (2.0) (1 / 2.0 = 0.50 * 100 = 50%. Therefore the 2.2 odds are inaccurate and pay 5% extra potential winning chances to the punter at no risk, we call this the Value Bet, as it gives a better advantage over the bookmaker. Now we know that if odds were below evens (2.0), the bookmakers would have an upper advantage over the punter.

In football betting it is a lot complex on calculating the probability. You cannot make an intelligent guess of odds about England winning the world cup.

You remain dependent upon the past performance of a team when you want to make a guess about its win in future matches. You need to observe the performance of a player or the whole team to be able to make such a prediction. There is also the factor of weather that you have to consider when making a prediction. In long events like a golf tournament or a test match in cricket, change of weather conditions can easily influence the outcome of the event. To make a guess about fair odds for Chelsea winning a long event like Premiership that will take place after 9 months is indeed a very difficult task.

As such, it is fair to say that calculation of fair odds in a long sporting event is only an intelligent guess rather than an exact mathematical calculation. Punters often take a cue from the fair odds given by bookmakers and they stand to make huge profits when they are able to spot a mistake in their predictions.