Journal of Portfolio Management, 40(5), 94–107 ·
SSRN
Correcting for Selection Bias, Backtest Overfitting, and Non-Normality. When a strategy is chosen as the best of many backtested configurations, its Sharpe ratio is inflated even if all candidates are noise. The DSR deflates the observed Sharpe for the number of trials, sample length, and return skew/kurtosis. Basis for the Stock Wizard champion/challenger gate: a re-optimized policy only replaces the live one if its deflated Sharpe clears a high confidence bar.