Public evidence

engineering.measurement.error

Machine-checked verification for calculation version 1.0.0 · tier engine_tested

Open calculator API Capability Download JSON MCP Review policy

Verification

6/6 calculation tests · Production surface contract 4/4

Golden tests 0 / 0
Boundary tests 3 / 3
Property tests 3 / 3
Production surface contract 4 / 4
Engine tested Yes
Source checked Yes
Artifact integrity PASS
Production attestation Embedded snapshot: STALE · Last attested schema matched 1.0.0 snapshot / local build · Semantic contract ✓ · Last attestation PASS · current evidence changed · re-attestation required · Public/cache ✓ · Origin ✓ · Live production status PASS (0 stale; 164 CURRENT) @ 2026-09-16T06:44:24.909Z
Semantic contract PASS
Evidence attested at 2026-09-16T06:44:24.203Z
Last production check 2026-09-16T06:44:24.203Z
Public / cache PASS
Origin PASS
Supplemental domain review Not performed
Named expert review Not performed

release artifacts aligned PASS
schema valid input executes PASS
engine success output validates schema PASS
schema rejects incomplete input PASS

Fingerprint sha256:057b1acfa986f0213d576cf63b66e8b9129be9b4ac717e2983db545641ef7d2e

Input schema sha256:3a5a70db41b37dbb0d94880432d51c4c4b34acd8d055a046a523ec35edd8d11c · Output schema sha256:a672d995cb1c232851f9262ced9a47d6550ff9fde97e2bb435ac35ab286f47ce · 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.

Build & scope

Engine identity and declared limitations.

Tool: measurement-error
Engine: measurement-error
Engine build: 2026-09-15
Evidence core: 2026-09-15T11:09:48.251Z
Rendered: 2026-09-16T22:03:43.738Z
Last reviewed: —

Assumptions

VIM measurement error ε = ylab − xref (signed). Relative error is ε/xref when xref ≠ 0.
Not percent error (×100), not En, not zeta, not z-score, and not an ILAC G8 spec decision.

Limitations

Signed error — this page does not multiply by 100 (that is percent error)
Not En, zeta, or z-score (those divide by U, u, or σ_pt)
Not an ILAC G8 specification decision
Relative error is undefined when xref = 0

Sources

Standards and references supporting this tool specification. Methods are listed separately — they are algorithms, not bibliographic sources.

JCGM 200:2012 — International vocabulary of metrology (VIM) — 2.16 measurement error; 2.17 relative measurement error
Supports: ε = measured quantity value minus a reference quantity value; relative error = ε / reference
ISO 13528 — Statistical methods for use in proficiency testing by interlaboratory comparison — z, zeta, and En are different contracts
Supports: This page does not compute a PT score; it reports the raw signed error

Published checks

Golden, boundary, and property cases included in this evidence build.

ID	Kind	Status	Detail
`boundary-err`	boundary	pass	Expected error=0.5 · abs_error=0.5 · relative=0.25 · Actual error=0.5 · ylab=2.5 · xref=2 · abs_error=0.5 · relative=0.25
`boundary-err-zero`	boundary	pass	Expected error=2.5 · Actual error=2.5 · ylab=2.5 · xref=0 · abs_error=2.5
`boundary-err-missing`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`property-err`	property	pass	0.5
`property-err-alias`	property	pass	2
`property-err-zero`	property	pass	null