engineering.measurement.cochran

Three distinct suites: educational examples on the calculator page, this legacy regression count (9/9 golden + boundary), and the CVP verification suite below. They are not the same number. Property, metamorphic, round-trip, O3, and interface statuses/checks are recorded in the CVP Manifest . SKIP (0/0) means that suite has no published vectors.

This calculator CURRENT · Public schema 1.0.1 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓

CVP verification suite

Protocol checks from the Evidence Manifest. Distinct from the legacy regression suite above. Verification revision 2026-09-25.o2-o3. Calculation version 1.0.1. CVP 1.0.0-proposed. 4/4 golden · 5/5 CVP boundary · 5/5 invalid · 1/1 property · 1/1 metamorphic · 8/8 O3 · 2/2 cross-interface · 6/6 CVP contract. digest 9eb4c2d716f3. O2: Cochran C = s_max² / Σ s_i² vs a separate-module identity (≤2 ULP). Not a Ccrit verdict. ≤2 ULP vs O3 applies only to the published tabulated Cochran vectors. Not a Ccrit verdict.

• Golden (oracle-backed) 4 / 4
• CVP boundary 5 / 5
• Invalid input 5 / 5
• Property 1 / 1
• Metamorphic 1 / 1
• O3 high-precision 8 / 8
• Cross-interface 2 / 2
• CVP contract 6 / 6
• Interfaces PASS · UI (SSR) / REST / MCP
• Interface claim ui-ssr is query-result HTML, not a live browser session. Error-path engine·REST·MCP 1/1 (status, code, calculation_version). SSR compared on URL-canonical requested calculations; empty query is idle (not an error) and JSON-typed object/array inputs are REST/MCP-only.
• Verified scope ISO 5725-2 C = s_max² / Σ s_i² from k≥2 stated laboratory s_i, + O3 mpmath tabulated Cochran C.
• Assurance Engineering
• Deferred Not a Ccrit verdict and not pooled s_p.

• release artifacts aligned PASS
• schema output required declared PASS
• schema valid input executes PASS
• engine success output validates schema PASS
• schema rejects incomplete input PASS
• rest success payload validates schema PASS

Fingerprint sha256:f060238442b0e0c8c0a5ae96ded9ef8b5da0fd34de76230eb9abdd22efd347b6

Input schema sha256:1fa7f4bad9eafe23562601eb868af034c62528ec37bbedeb038463599a3d561a · Output schema sha256:ab0c31baf89f18c4d0ae79def9aaa3f1b2052fc2c2758407fdf444201a29d34f · Build-time SHA-256 digests prove published artifacts agree with each other (release_integrity.scope=workspace). Production attestation GETs canonical URLs twice (public/cached view and origin), including Capability HTML, via npm run attest:production --write (published at /.well-known/calculatorx-production-attestation.json) and fails if the public Capability page advertises a different calculation_version. This is artifact consistency, not an independent immutable release log.

Tool

cochran

Engine

cochran

Engine build

2026-09-24

Evidence core

2026-09-24T23:14:39.755Z

Rendered

2026-10-23T01:27:11.203Z

Last reviewed

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Assumptions

• ISO 5725-2 Cochran C = s_max² / Σ s_i² from k≥2 stated laboratory sample standard deviations. k=1 is rejected.
• s_i ≥ 0. All-zero s is rejected (Σ s² must be > 0).
• Not pooled s_p, not Hartley's F_max, and not a tabulated Ccrit pass/fail.

Limitations

• Takes stated laboratory s_i — not a sample of observations
• k=1 is rejected so this cannot wrap identity C=1
• All-zero s is rejected (Σ s² must be > 0)
• Does not compare C to a tabulated Ccrit(p, n, α)
• Not pooled s_p and not Hartley's F_max