variance

Variance is the magnitude of fluctuation of actual results around expected value. Short-term winning streaks, losing streaks, and coolers in poker are all manifestations of variance.

Detailed Explanation

Variance is the core feature that makes poker poker. If variance didn't exist, every decision would resolve instantly, skill gaps would clear within a few hands — but then poker wouldn't have so many amateurs willing to play.

Two key facts about variance:

1. Variance can mask skill gaps short-term: in 100 hands, an amateur can beat a pro; in 100,000 hands, the pro inevitably beats the amateur
2. Variance is related to playing style: aggressive play (wide 3bets, many bluffs) has higher variance; conservative play has lower variance

The standard variance metric is standard deviation (bb/100): 6-max NLHE cash typically runs around 100-150 bb/100. This means a 1,000-hand sample has roughly a ±6-9 bb/100 95% confidence interval relative to true win rate.

Common Use Cases

• Bankroll management: more variance, more bankroll. The common guideline is 30-50 buy-ins minimum for cash
• Coping with downswings: long-run +EV players also necessarily experience 10-20 buy-in downswings — normal variance, not a skill problem
• Mental training: accepting variance is the foundation of pro mindset

Common Mistakes

• Evaluating yourself by short-term results: a 10k-hand sample is nowhere near enough to show your true win rate
• Over-reacting to downswings: panic leads to tilt, larger sizing, moving down — turning into a real -EV cycle
• Ignoring variance feedback on decisions: good players hold strategy in a downswing; bad players change strategy because of short-term results