ReviewsREV-026

Read-only synthetic sample

Read-only synthetic sample · No real applicant data

REV-026 / Northstar Community Bank

Consumer underwriting Q1–Q2 2026

Unsecured consumer installment · Nimbus v4.1 → v4.2 · Jan 1 – Jun 30, 2026

MCMaya Chen · prepared / Ellis Morgan · independent reviewer

Draft
Data qualification
Testing
Challenge
Management response
Retest
Complete

12,481 applicationsv4.1 → v4.2 March 181 unresolved findings7 preserved runs

Review scope

Can a qualified reviewer reconstruct the decision, challenge its evidence and preserve the response and retest?

System: Nimbus Consumer Score · model + eligibility policy + cutoff + human override + reason mapper
Snapshot: SYS-026.2 / DS-026.2
Period: Jan 1 – Jun 30, 2026
Prepared / independent reviewer: Maya Chen / Ellis Morgan
Current boundary: Descriptive synthetic review. No causal or legal adjudication.
Open question: What policy rationale and action will resolve FL-024?

!

Two different retest outcomes

FL-024’s screen persists after the analysis-specification change. AA-009’s corrected mapper replay is supported; the original inconsistent notice remains inspectable.

Findings and next actions

Finding / observation	Materiality	Owner	Status	Next action
AA-009 · Reason provenance inconsistent in original noticeOriginal notice cites credit history, which is absent from the supplied principal-factor record. Corrected mapping replay is supported by the same record; production deployment has not been assessed.	Moderate	Maya Chen	Closed	Closure applies to the synthetic mapper replay only. Production notice remediation would require separate evidence.
FL-024 · Covered-population outcome differenceThe configured descriptive screen is triggered within qualified bureau strata. It is not a finding about applicants without supplied proxies or a legal conclusion.	Moderate	Maya Chen	Retest required	Remediation did not resolve the descriptive screen. Request a new action plan; retain the original result.

Unified review chronology

Snapshot registered · DS-026.2Maya Chen · Dataset

Generated synthetic extract; no bank ingestion.

Inspect previous and new state

{
  "before": null,
  "after": {
    "hash": "fnv1a32-1157db84",
    "rows": 12481
  }
}

Sep 9, 9:10 AM ET

Protocol approved · CFG-01Ellis Morgan · Configuration

Synthetic reviewer choice: descriptive AIR < 0.80 prompts investigation, not a legal verdict. At least 30 independent applicant records per cohort per stratum is an illustrative stability gate, not a power analysis. Use the covered population only; no inference to missing proxy records.

Inspect previous and new state

{
  "before": null,
  "after": {
    "id": "CFG-01",
    "methodVersion": "Stratified Screen v2.0",
    "channel": "Partner Marketplace",
    "version": "v4.2",
    "from": "2026-01-01",
    "to": "2026-06-30",
    "threshold": 0.8,
    "minimum": 30,
    "reference": "Cohort B",
    "stratify": true,
    "population": "covered-only",
    "maxMissing": 0.2,
    "rationale": "Synthetic reviewer choice: descriptive AIR < 0.80 prompts investigation, not a legal verdict. At least 30 independent applicant records per cohort per stratum is an illustrative stability gate, not a power analysis. Use the covered population only; no inference to missing proxy records.",
    "approvedBy": "Ellis Morgan",
    "createdAt": "2026-09-10T14:00:00Z"
  }
}

Sep 10, 10:00 AM ET

Descriptive test executed · RUN-01Maya Chen · Test run

Partner covered-population screen

Inspect previous and new state

{
  "before": null,
  "after": {
    "configId": "CFG-01",
    "result": "Triggered configured screening rule"
  }
}

Sep 11, 9:00 AM ET

Descriptive test executed · RUN-02Maya Chen · Test run

Aggregate versus segmented sensitivity

Inspect previous and new state

{
  "before": null,
  "after": {
    "configId": "CFG-02",
    "result": "No screen trigger"
  }
}

Sep 11, 10:00 AM ET

Descriptive test executed · RUN-03Maya Chen · Test run

Branch null-result check

Inspect previous and new state

{
  "before": null,
  "after": {
    "configId": "CFG-03",
    "result": "No screen trigger"
  }
}

Sep 11, 11:00 AM ET

Descriptive test executed · RUN-04Maya Chen · Test run

Small-population qualification

Inspect previous and new state

{
  "before": null,
  "after": {
    "configId": "CFG-04",
    "result": "Interpretation withheld"
  }
}

Sep 11, 12:00 PM ET

Descriptive test executed · RUN-05Maya Chen · Test run

Full-population coverage qualification

Inspect previous and new state

{
  "before": null,
  "after": {
    "configId": "CFG-05",
    "result": "Interpretation withheld"
  }
}

Sep 11, 1:00 PM ET

Descriptive test executed · RUN-07Maya Chen · Test run

Pre-change Nimbus v4.1 sensitivity

Inspect previous and new state

{
  "before": null,
  "after": {
    "configId": "CFG-07",
    "result": "No screen trigger"
  }
}

Sep 11, 2:00 PM ET

Finding opened · FL-024Maya Chen · Finding

Covered population screen requires explanation; missingness bounds interpretation.

Inspect previous and new state

{
  "before": null,
  "after": {
    "status": "Open"
  }
}

Sep 12, 10:30 AM ET

Finding opened · AA-009Maya Chen · Finding

Original reason contradicts the supplied principal-factor record.

Inspect previous and new state

{
  "before": null,
  "after": {
    "status": "Open",
    "evidence": [
      "EV-002",
      "EV-003"
    ]
  }
}

Sep 12, 11:00 AM ET

Challenge created · CH-018Maya Chen · Challenge

Request supporting evidence

Inspect previous and new state

{
  "before": null,
  "after": {
    "originId": "FL-024",
    "question": "Provide the channel specification and document the change; second-line analysis is retained separately."
  }
}

Sep 13, 12:15 PM ET

Finding state changed · FL-024Maya Chen · Finding

Model-owner explanation requested.

Inspect previous and new state

{
  "before": {
    "status": "Open"
  },
  "after": {
    "status": "Under challenge",
    "challengeId": "CH-018"
  }
}

Sep 13, 12:16 PM ET

Challenge created · CH-019Maya Chen · Challenge

Request supporting evidence

Inspect previous and new state

{
  "before": null,
  "after": {
    "originId": "AA-009",
    "question": "Reconcile notice reason M-17 with the supplied principal factors."
  }
}

Sep 13, 1:00 PM ET

Model-owner response received · CH-018Daniel Ortiz · Challenge

We disagree that a difference alone warrants a model change. The original specification omitted channel sensitivity. We have supplied specification B; no decision-policy or model outputs changed.

Inspect previous and new state

{
  "before": {
    "status": "Awaiting response"
  },
  "after": {
    "status": "Response received",
    "responseId": "RESP-018-1",
    "artifactIds": [
      "EV-008",
      "EV-010"
    ]
  }
}

Sep 15, 2:05 PM ET

Review progressed to retest · REV-026Maya Chen · Review

Responses and changed specifications received; preserve original findings.

Inspect previous and new state

{
  "before": {
    "stage": "Management response"
  },
  "after": {
    "stage": "Retest"
  }
}

Sep 16, 8:00 AM ET

Descriptive test executed · RUN-06Maya Chen · Test run

FL-024 sensitivity retest; no changed decision outcomes

Inspect previous and new state

{
  "before": null,
  "after": {
    "configId": "CFG-06",
    "result": "Triggered configured screening rule"
  }
}

Sep 16, 8:30 AM ET

Finding state changed after retest · FL-024Maya Chen · Finding

Screen persists. Updated analysis specification did not establish remediation.

Inspect previous and new state

{
  "before": {
    "status": "Under challenge"
  },
  "after": {
    "status": "Retest required",
    "retestId": "RT-024"
  }
}

Sep 16, 8:35 AM ET

Response disposition recorded · CH-018Maya Chen · Challenge

The scope explanation is supported, but changing the analysis does not remediate the persisting outcome screen. Request policy rationale and a new action plan.

Inspect previous and new state

{
  "before": {
    "status": "Response received"
  },
  "after": {
    "status": "Additional evidence required",
    "responseId": "RESP-018-1"
  }
}

Sep 16, 9:10 AM ET

Model-owner response received · CH-019Daniel Ortiz · Challenge

M-17 incorrectly mapped utilization to credit-history wording. MAP-3.5-TEST maps utilization to the corresponding stated factor. The original notice remains preserved. Replay only, not a production release.

Inspect previous and new state

{
  "before": {
    "status": "Awaiting response"
  },
  "after": {
    "status": "Response received",
    "responseId": "RESP-019-1",
    "artifactIds": [
      "EV-003",
      "EV-014"
    ]
  }
}

Sep 16, 9:30 AM ET

Replay submitted for independent review · AA-009Maya Chen · Finding

Corrected mapper replay supplied; independent review still required.

Inspect previous and new state

{
  "before": {
    "status": "Open"
  },
  "after": {
    "status": "Retest required",
    "retestId": "RT-009"
  }
}

Sep 16, 10:05 AM ET

Response disposition recorded · CH-019Ellis Morgan · Challenge

Compared original notice, principal factors and corrected replay. Both replay reasons are supported. Closure scope is the synthetic mapping defect only.

Inspect previous and new state

{
  "before": {
    "status": "Response received"
  },
  "after": {
    "status": "Supported",
    "responseId": "RESP-019-1"
  }
}

Sep 16, 11:00 AM ET

Finding closed · AA-009Ellis Morgan · Finding

EV-014 replay is supported. Closure limited to sandbox mapping; no production remediation claim.

Inspect previous and new state

{
  "before": {
    "status": "Retest required"
  },
  "after": {
    "status": "Closed",
    "retestId": "RT-009"
  }
}

Sep 16, 11:05 AM ET