Standard deviation
Standard deviation measures how far your results typically stray from your win rate. It is the key input to variance and risk-of-ruin maths.
In short: The typical size of your swings.
- Category
- Variance
- Best use
- Session review and bankroll decisions
- Related page
- Standard deviation guide
Why Standard deviation matters
Standard deviation measures how far your results typically stray from your win rate. It is the key input to variance and risk-of-ruin maths. Variance terms matter because live samples lie for longer than most players expect. A graph can be up or down for months without proving very much. The value is not comfort; it is knowing whether the current stretch fits the model or points to a real leak.
Worked example
Live full-ring cash often shows a lower standard deviation than short-handed online play. The useful part is not the label itself; it is the decision it changes. If the example changes your stake, stop-loss, review queue or next study block, write it cleanly in the log.
How to apply it
Keep the decision separate from the outcome. Use win rate, standard deviation and sample size to build a range, then compare the current run against that range. If the run is normal, keep logging and review spots. If it is outside the band, dig harder. For Standard deviation, the practical question is whether the label changes a bankroll, session or study decision. If it does not change a decision, it belongs in a note, not in the headline read.
Overshove treats variance as a review input. Log every session, including the ugly ones, then read the confidence band beside the point estimate. Mark the hands and leaks separately, so running bad does not excuse playing bad. Use the same spelling every time, then link it back to standard deviation guide so the page, calculator or guide beside the term does useful work.
Common mistakes
- +Calling every losing stretch a downswing.
- +Calling every heater a new win rate.
- +Letting a point estimate stand on its own without a confidence band.
Questions players actually ask
How should I use Standard deviation in a session log?
Use Standard deviation as a decision label, not decoration. Log the raw session first, then attach the term only where it explains a stake, bankroll, variance or study choice you can review later.
What is the common mistake with Standard deviation?
The common mistake is reading the term without the sample and context behind it. In live cash, a clean label still needs stake, hours, stack depth, cost and result data before it tells you anything reliable.