In betting, variance is the difference between expected and actual results. A 55% win-rate bettor flipping 100 coins can easily finish anywhere from 45 to 65 wins. This is why bankroll management matters more than any single pick — you need capital to survive the downswings.
Math & probability
Variance
The natural swing in outcomes. Even +EV bettors lose over sample sizes of hundreds of bets.
Example
A sharp bettor hitting 54% on -110 lines can still have a losing month. Over 1,000 bets, the edge shows up.
Related terms
Bankroll management
Sizing bets as a fixed percentage of your total wagering capital — the #1 discipline for long-term survival.
Kelly criterion
The mathematically optimal stake size given your edge. Most sharp bettors use a fractional version.
Expected value (EV)
The average profit per bet if you could replay the same situation thousands of times.