Public evidence

engineering.measurement.accuracy

Machine-checked verification for calculation version 1.0.0 · tier engine_tested

Open calculator API Capability Download JSON MCP Review policy

Verification

9/9 calculation tests · Production surface contract 4/4

Golden tests 0 / 0
Boundary tests 5 / 5
Property tests 4 / 4
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:dfbd1cca818a32aaffa19c550285cdcbb3c67f1ad996938e58d5c026f082dafa

Input schema sha256:1aada2be081699b8a56d82857bc19bffd09559dbcbf8eba81f222516a937049b · Output schema sha256:7c6882055647420d2639d9d3a928cfcef8b16a978c2d9e0a9d6ce554875d9748 · 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: accuracy
Engine: accuracy
Engine build: 2026-09-16
Evidence core: 2026-09-16T21:07:40.795Z
Rendered: 2026-09-16T22:38:08.854Z
Last reviewed: —

Assumptions

VIM trueness: signed bias = x̄ − xm from repeats on a master. s may be zero.
Not a single-shot measurement error, not Type A u_A = s/√n, and not Type-1 Cg (no T).

Limitations

Signed bias from a sample mean — not a single-shot measurement error ε
Does not report Type A u_A = s/√n
Does not need a tolerance T (that is Type-1 Cg/Cgk)
s = 0 is valid; n = 1 with ddof = 1 is VALUE_OUT_OF_RANGE

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) — 2.13 measurement accuracy; 2.14 measurement trueness; 2.18 measurement bias
Supports: Accuracy is qualitative; trueness is closeness of the mean to a reference; bias is the estimate of a systematic measurement error
ISO 5725-1 — Accuracy (trueness and precision) of measurement methods and results — Trueness as bias of the mean versus a reference
Supports: This page reports signed bias of the sample mean; it does not report a precision index as the product

Published checks

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

ID	Kind	Status	Detail
`boundary-acc`	boundary	pass	Expected bias=-1 · abs_bias=1 · xbar=7 · s=1 · Actual n=3 · bias=-1 · abs_bias=1 · xbar=7 · s=1 · xm=8 · ddof=1
`boundary-acc-zero`	boundary	pass	Expected bias=0 · s=1 · Actual n=3 · bias=0 · abs_bias=0 · xbar=8 · s=1 · xm=8 · ddof=1
`boundary-acc-flat`	boundary	pass	Expected bias=0 · s=0 · Actual n=3 · bias=0 · abs_bias=0 · xbar=8 · s=0 · xm=8 · ddof=1
`boundary-acc-n1`	boundary	pass	Expected VALUE_OUT_OF_RANGE · Actual VALUE_OUT_OF_RANGE
`boundary-acc-missing`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`property-acc`	property	pass	-1
`property-acc-zero`	property	pass	0
`property-acc-flat`	property	pass	0
`property-acc-alias`	property	pass	-1