You tested 8 strategies and one looks brilliant. PBO asks the question most backtests never face: among everything you tried, how likely is the winner just the luckiest loser? You ran 8 versions of a strategy.
Source: [Dev.to](https://dev.to/dronpancholi/pbo-explained-in-plain-english-the-probability-your-best-backtest-is-a-fluke-581e)