Phase 1.7 follow-up to Script 38's per-CPA convergence. Tests
whether the convergence holds at signature granularity, preempting
"per-CPA aggregation washes out signal" reviewer attacks.
Three signature-level labels per Big-4 signature (n=150,442):
L1 PaperA non_hand iff cos > 0.95 AND dh <= 5
L2 K=3 perCPA hard assignment under per-CPA-fit components
L3 K=3 perSig hard assignment under fresh signature-level fit
Component comparison (per-CPA vs per-signature K=3):
Component Per-CPA cos/dh/wt Per-Sig cos/dh/wt
C1 hand-leaning 0.9457/9.17/0.143 0.9280/9.75/0.146
C2 mixed 0.9558/6.66/0.536 0.9625/6.04/0.582
C3 replicated 0.9826/2.41/0.321 0.9890/1.27/0.272
Component drift modest: max |dcos| = 0.018, max |ddh| = 1.15.
Cohen kappa (binary, 1 = replicated):
PaperA vs K=3 perCPA kappa = 0.6616 substantial
PaperA vs K=3 perSig kappa = 0.5586 moderate
K=3 perCPA vs K=3 perSig kappa = 0.8701 almost perfect
Per-firm binary agreement PaperA vs K=3 perCPA:
Firm A 86.13%, KPMG 77.46%, PwC 82.64%, EY 85.01%.
Verdict: SIG_CONVERGENCE_MODERATE (all kappas >= 0.40; per-CPA
aggregation captures most signature-level structure).
Implication for v4.0: per-CPA K=3 is robust to aggregation level
(kappa = 0.87 vs per-signature fit). The modest disagreement
between K=3 and Paper A's box rule (kappa 0.56-0.66) reflects
different decision geometries -- K=3 posterior soft boundary vs
Paper A rectangle box -- not a fundamental signal disagreement.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
