MaineblockFinance
Statistics for investors
Plain-English guides on the statistics that actually matter when money is on the line — written by a working statistician, not a content mill.
Why backtests lie
Overfitting and the multiple-comparisons problem: why the strategy that “worked” on historical data usually didn't.
The earnings beat is mostly noise
Why quarterly earnings surprises barely move long-run returns — and the two questions that separate signal from noise.
Position sizing without blowing up
Expected value, base rates, and the Kelly fraction — how much to risk on any idea.
Volatility, drawdown, and what “annualized” hides
A single return number conceals the ride you actually take.
Correlation isn't diversification
What actually lowers portfolio risk — and what just looks like it does.
The Investor Stats Cheat Sheet
A free two-page PDF: expected value, Kelly sizing, Sharpe, sample-size math, and how to read a p-value without fooling yourself. Plus new tools as they ship.