Bettors should always look for a mathematical edge rather than rely on their impulses. Learning how to use the Kelly Criterion, for example, is a great way for bettors to determine how much they should stake. Read on to find out.
Prior to placing a bet bettors should consider six important questions: who, what, when, where, why and how? But for this article, it is the how, as in how much to bet, we are interested in.
Popular staking method which suggests that stake should be proportional to the perceived edge.
Consider placing a bet on Dota 2's The International. We can adapt these questions accordingly:
- Who to bet on? Team Liquid
- What to bet on? Outright winner
- When to bet on? When the odds are posted
- Where to bet on? Pinnacle tend to offer the best odds
- Why bet on them? They seem to be under-priced
- How much? How much to bet on this outcome?
Most bettors tend to focus on the first five questions, typically using mathematical or statistical justifications on answering ‘why’ - often influenced by the do's and don'ts of esports betting.
In making financial decisions, the key issue is not only finding the adequate financial products to invest in but also deciding how to subdivide one’s portfolio. Similarly, an important question for a bettor is how much to wager?
Many papers recommend using the Kelly Criterion or a derivative of it - such as Dominic Cortis' paper from The Journal of Gambling Business and Economics. In essence, the Kelly Criterion calculates the proportion of your own funds to bet on an outcome whose odds are higher than expected, so that your own funds grow exponentially.
The Kelly Criterion formula is:
(BP - Q) / B
B = the Decimal odds -1
P = the probability of success
Q = the probability of failure (i.e. 1-p)
Using a coin as an example of Kelly Criterion staking
Consider you are betting on a coin to land on heads at 2.00. However, the coin is biased and has a 52% chance of ending up on heads.
In this case:
P= 0.52
Q = 1-0.52 = 0.48
B = 2-1 = 1.
This works out at: (0.52x1 – 0.48) / 1 = 0.04
Therefore the Kelly Criterion would recommend you bet 4%. A positive percentage implies an edge in favour of your bankroll, so your funds grow exponentially. You can also test the criterion for different values in this online sheet by using the code below.
Ultimately the Kelly Criterion offers a distinct advantage over other staking methods and Arbitrage methods as there is a lower risk. However, it does require precise calculation of the likelihood of an event outcome, and discipline of this method will not provide explosive growth of your bankroll.
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