Harmonic patterns and the Texas sharpshooter

[Shadow Trader]

Harmonic patterns, Gartley, Bat, Butterfly, Crab, use specific Fibonacci ratios between swing points to define reversal zones. Charts with perfect geometry look persuasive.

The Texas sharpshooter fallacy describes someone who fires at a barn wall, then paints a target around the tightest cluster of bullet holes. Harmonic patterns invite the same thing. With enough swing points and tolerance in the ratios, some pattern can be found at almost any turning point.

A rigorous approach fixes the tolerances in advance, scans automatically for patterns across a long dataset, and measures what follows each detection, compared with a baseline of randomly chosen turning points. Scanners exist, and the results of such tests, where published, are usually unimpressive.

The patterns may still provide useful structure for some traders, pushing them to wait for confirmation and define risk clearly. That discipline can matter more than the pattern itself.

The risk lies in treating a beautifully drawn pattern as evidence of an edge.

One safeguard is a pre-registered list. Write down the pattern, the entry, the stop and the target before the trade, timestamp it, and record the result. After a hundred entries, the success rate is a fact, not a feeling.

Has an automatic harmonic scanner been tested with fixed tolerances, and what did the hit rate look like?

[FXS Prop Desk]

A rigorous approach fixes the tolerances in advance, scans automatically for patterns across a long dataset, and measures what follows each detection, compared with a baseline of randomly chosen turning points.

The sharpshooter comparison fits because the reversal zone is drawn after the swings exist. A fair test fixes the ratio tolerances in advance, scans history for every pattern that qualifies, and counts the failures too. Most published harmonic examples are the winners only, which is the painted target.