# UTFANSWF v21 — Row 20 Layered Attribution Strength

**Context:** DIAGNOSTIC_NON_GATING. No physics, thresholds, datasets, parameters, or gate verdicts changed.

## Layer groups

| Group | Nodes | chi2 sum | RSS sigma |
|---|---|---:|---:|
| early/radial | CMB ell_A + BAO H(z=0.706) | 22.407716 | 4.733679 |
| late/transverse | BAO D_M(z=0.706) + SN pivot + SH0ES | 44.855680 | 6.697438 |
| combined | all five key residuals | 67.263396 | 8.201426 |

## Sign consistency

| Quantity | Value |
|---|---:|
| sign score | 5/5 |
| sign fraction | 1.000000 |
| heuristic random sign probability | 0.062500 |

## Interpretation

- This strength test quantifies whether the layered sign pattern is strong enough to support formal attribution.
- All layered sign checks passed, supporting a coherent early/radial versus late/transverse split.
- Both sides of the split are independently strong: early/radial RSS exceeds 4 sigma and late/transverse RSS exceeds 5 sigma.
- The combined layered residual strength exceeds 7 sigma in RSS diagnostic magnitude.
- This does not prove a numerical H0 reconciliation; it supports a formal attribution claim that the tension is layered rather than single-parameter.

## Verdict

formal_layered_attribution_supported; diagnostic only; no physics, thresholds, datasets, parameters, or gate verdicts changed.
