Backtesting and overfitting
Level: Advanced 6 minutes · Last reviewed on Oct 13, 2026
A checks a rule on past prices. The danger: if you tweak the settings long enough, you almost always find a curve that looks good – even in pure chance. This is called . A test only becomes honest with data that was not used for tuning (), or with : learn, test, move on. The price series here is pure chance – every “edge” is luck.
Things to try
- Turn the sliders until the learning phase looks as good as possible. Then show the new data.
- Press “Find best setting” and compare the learning phase with the new data.
- Start the walk-forward and roll a new random series.
Quick check
Backtest your own list: backtest with Premium → (with account)
Educational content, not investment advice. Trading involves the risk of loss, up to a total loss. Risk notice