Win Rate vs. Sample Size
Look: a 55% win rate on ten hands is meaningless, but the same percentage over a thousand tells a story. Short bursts of luck fade; the law of large numbers screams consistency.
Confidence Intervals
Here is the deal: a confidence interval frames your win rate, giving you a safety net. 95% confidence? Means the true skill level sits somewhere in that band, not a blind guess.
Expected Value (EV) – The Bottom Line
By the way, EV is the gold standard. Multiply each outcome’s probability by its payoff, sum it up, and you see whether the game feeds you or drains you. Positive EV? Play. Negative? Walk away.
Variance and Standard Deviation
Variability tells you how wild the swings can get. High variance? Brace for roller‑coaster sessions. Low variance? Smooth sailing, but expect modest profits.
Bankroll Management Ratios
Stake size equals a fraction of your bankroll—usually 1% to 3% per hand. The Kelly Criterion sharpens this: (bp‑q)/b, where b is the odds, p your win probability, q = 1‑p. Follow it, and you dodge ruin.
Risk of Ruin
Risk of ruin quantifies the chance you’ll go broke before hitting your target. Plug your win rate, variance, and stake size into the formula; a tiny percentage means you’re safe, a big one screams caution.
Sharpe Ratio for Card Players
Adapt the Sharpe Ratio: (EV‑risk‑free rate) / standard deviation. It stacks your return against volatility. A ratio above 1.5? Congrats, you’ve got an edge worth scaling.
Edge Decay and Tracking
Edges erode. Monitor your metrics weekly; a slipping win rate signals a shift in opponent behavior or table dynamics. React fast, or you’ll bleed.
Actionable Tip
Track every hand, calculate EV, variance, and the Kelly stake on the fly, then compare the live win rate against its confidence interval. If the interval no longer embraces your target win rate, cut the stake immediately.
