Understanding the Purpose
Kelly tells you what fraction of your bankroll to wager to maximize long run growth when you have a positive expectation.
If you do not have an edge, Kelly will not recommend a bet.
The Importance of p
Your edge comes from estimating p more accurately than the market.
Bet Better’s data models provide objective probability estimates you can use for disciplined staking.
Fractional Kelly
Full Kelly can produce large swings. Many bettors reduce variance by using Fractional Kelly, such as half Kelly or quarter Kelly.
This keeps the structure of Kelly while lowering drawdowns.
FRACTIONAL KELLY EXAMPLE
Full Kelly result: 6%
Half Kelly stake: 3%
> Lower variance, same disciplined logic.
Pair this with bankroll discipline:
Bankroll Management Guide.
FAQ
What is the Kelly Criterion used for?
It estimates an optimal bankroll fraction to stake when you have an edge, aiming to maximize long run growth.
Why do bettors use Fractional Kelly?
Because full Kelly can be volatile. Fractional Kelly reduces variance and drawdowns while keeping a consistent edge based staking approach.
What does a negative Kelly number mean?
It suggests you do not have positive expected value at the offered odds, so Kelly would recommend passing.