Deep dive — methodology

How the A / B / C determination is derived

Every $499 Snapshot lands on exactly one overall determination. Not a color code, not a health score — an A/B/C determination tied to attestation stance. Here is exactly how it is derived.

The three categories

Category	Meaning	Attestation stance
A	No high-severity drift events. No group-differential signal. Baseline vs recent distributions match within threshold.	Sufficient for attestation. Signed evidence available on file.
B	Medium-severity drift or single-event high-severity without group-differential signal. Aggregate metrics stable.	Conditional. Named remediation + re-audit within defined window supports attestation.
C	Multiple high-severity drift events + group-differential signal fired.	Insufficient. Lender should not represent the AI as compliance-defensible until remediation completes.

The evidence chain

Sensor thresholds active during the audit:
- Mean-shift threshold: 1.5 standard deviations from baseline
- Variance-ratio threshold: 1.5x baseline
- KL-divergence threshold: 0.2
- Group disparate-impact differential threshold: 12% shift across applicant groups
Event classification:
- Any single-threshold cross → medium-severity event
- KL-divergence > 0.5 OR group-differential signal → high-severity event
Category assignment:
- 0 high-severity + 0 group-differential → A
- 1-2 high-severity, no group-differential signal → B
- ≥ 3 high-severity or any group-differential signal fired → C

Why this sample lands on C

10 high-severity distributional-drift events across the 90-day audit period. H3 fired 8 times (Days 44, 51, 58, 65, 72, 79, 86, plus one at Day 89 aggregated). H5 fired twice (Days 30, 37, 79). Either the count alone or the H3 cluster alone is sufficient for C. Both are present. The determination is not marginal.

Why the A/B/C structure matters

Continuous-scale scores (0-100 dashboard, red / yellow / green tri-lights, "health-score" percentages) push operators toward "just above the threshold" gaming. A/B/C determinations force a single stance question:

Would you sign the attestation as-is today? A/B/C answers the question that regulators, boards, GSE counterparties, and carriers actually ask — instead of the question the vendor's dashboard prefers.

How does this help me?

Knowing your category BEFORE the CFPB exam / DOJ referral / HUD letter / board deck lands is the whole value of the $499 discipline.

Read: The value of knowing your category first →

$499 Snapshot. 3 business days.

Get your lender's A / B / C determination on your actual AI surface — before someone else's question forces the answer.

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