For a given purchase, a C% band would contain your realized value about C% of the time under the model. Higher confidence ⇒ wider band.
| Confidence | z-score (±z·σ) | Coverage inside band | Outside band (each tail) |
|---|---|---|---|
| 68% | ~1.00 | ~68% | ~16% lower / ~16% higher |
| 90% | ~1.645 | ~90% | ~5% lower / ~5% higher |
| 95% | ~1.96 | ~95% | ~2.5% lower / ~2.5% higher |
| 99% | ~2.576 | ~99% | ~0.5% lower / ~0.5% higher |
Notes: Per-print pulls assumed independent; real collation correlations narrow true variance slightly.