How I define a failed breakout in numbers, not by feel

[FXS London Scalper]

Notes that say "breakout failed" without a definition make any statistics useless. A rule that can be checked on a chart fixes that.

One definition for EURUSD and GBPUSD on M1:

• Price closes at least 2 pips beyond the level, for example the Asian high.
• Within the next 10 bars, price closes back inside the range by at least 2 pips.
• The maximum excursion beyond the level stayed under 8 pips.

If all three are true, it's a failed breakout. If price went further than 8 pips before coming back, count it as a breakout that reversed later, which is a different situation.

Once the rule exists, you can apply it to past London opens and count how often failures occur, then test fading them with a stop beyond the excursion high. Expect the setup to be infrequent, perhaps a few times a week, so samples build slowly.

The numbers 2, 10 and 8 are arbitrary and could be tuned, but it's better to fix them before looking at results than to change them afterwards. How do others define failure? Time based, distance based, or something else?