Do Inside Days Predict Breakouts?
https://fxabsolute.com/stats/GBPUSD.json.
Across nine pairs
| Pair | Inside days | Next day wide | vs 25% base | Count |
|---|---|---|---|---|
| AUD/USD | 13.6% | 28.6% | +3.6 | 182 |
| USD/JPY | 15.5% | 25.9% | +0.9 | 205 |
| EUR/JPY | 13.3% | 24% | -1.0 | 175 |
| AUD/CAD | 14.4% | 23.7% | -1.3 | 190 |
| USD/CAD | 11.1% | 22.5% | -2.5 | 151 |
| EUR/USD | 13.6% | 22% | -3.0 | 182 |
| GBP/JPY | 15.4% | 21.5% | -3.5 | 209 |
| GBP/USD | 13.7% | 20.9% | -4.1 | 182 |
| EUR/GBP | 14.2% | 19.6% | -5.4 | 189 |
Reading a negative result properly
This does not prove inside-bar strategies lose money. It tests one specific claim — that an inside day raises the odds of an unusually wide day next — and that claim does not survive contact with 182 inside days on GBP/USD alone.
A strategy can still work for other reasons: a defined risk level, a clear invalidation, a filter that keeps the trader out of worse setups. What it cannot claim is the mechanism. Publishing the mechanism as fact when the data disagrees is how a strategy survives long after its reasoning has stopped being true.
Why the opposite result is plausible
An inside day is, by definition, a contraction. Volatility clusters — a quiet day is more likely to be followed by another quiet day, for the same reason a wide one is followed by a wide one. Seen that way the finding is not surprising at all; it is the same clustering working in the direction nobody quotes.
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Questions
Do inside days lead to breakouts?
Not in this data. On GBP/USD an inside day is followed by a top-quartile range day 20.9% of the time, below the 25% base rate. Only 2 of the nine pairs measured beat chance at all.
How common are inside days?
13.7% of GBP/USD trading days — 182 in the sample.
Does this mean inside bar strategies do not work?
No. It tests one claim — that an inside day raises the odds of a wide day next — and that claim fails. A strategy can still be sound for reasons of risk definition rather than prediction.