Public evidence

engineering.uncertainty.weighted_mean

Machine-checked verification for calculation version 1.0.0 · tier engine_tested

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Verification

8/8 calculation tests · Production surface contract 4/4

Golden tests 0 / 0
Boundary tests 5 / 5
Property tests 3 / 3
Production surface contract 4 / 4
Engine tested Yes
Source checked Yes
Artifact integrity PASS
Production attestation Embedded snapshot: unpublished · Build schema 1.0.0 ready · Semantic contract ✓ · Attestation report not published on origin · Live production status STALE (1 capability; 156 remain CURRENT) @ 2026-09-14T03:54:53.650Z
Semantic contract PASS
Evidence attested at 2026-09-14T00:43:05.498Z
Last production check 2026-09-14T00:43:05.498Z
Public / cache —
Origin —
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 sha256:690bac2d8e20a93e8cca32e4fecdacc18c8113953b2d45d189c09a8967be26a1

Input schema sha256:594f95e5eb164d2294ae9facc1072431a206ee924de5f9c36e597b7d0967a28a · Output schema sha256:3a0ccab6b8ecc7c51ed5199973a1566503dba446a09912e3441d5f4791e867ae · 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: weighted-mean
Engine: weighted-mean
Engine build: 2026-09-15
Evidence core: 2026-09-15T21:59:41.132Z
Rendered: 2026-09-15T23:38:12.902Z
Last reviewed: —

Assumptions

JCGM 100:2008 H.3 inverse-variance weighted mean of independent uncorrelated results of the same measurand
Each u_i is a standard uncertainty greater than zero
Not combined RSS, not Type A u_A = s/√n, and not GUM propagate
χ² / Birge are diagnostics, not a pass/fail

Limitations

Independent uncorrelated results of the same measurand — not RSS of a measurement model
Does not compute Type A u_A = s/√n from repeats without individual u_i
Does not compute expanded U = k·u_w
χ² / Birge are diagnostics, not a pass/fail verdict

Sources

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

JCGM 100:2008 — Evaluation of measurement data — Guide to the expression of uncertainty in measurement (GUM) — H.3 Measurements sampled from a distribution: weighted mean
Supports: x_w = Σ(x_i/u²(x_i))/Σ(1/u²(x_i)); u²(x_w) = 1/Σ(1/u²(x_i)) for independent uncorrelated results of the same measurand
JCGM 100:2008 — Combined standard uncertainty (RSS of a measurement model) — 5.1.2 uncorrelated input quantities
Supports: RSS u_c = √Σ (c_i u_i)² is a different contract; this page does not combine a measurement model

Published checks

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

ID	Kind	Status	Detail
`boundary-wm`	boundary	pass	Expected n=4 · x_w=5 · u_w=0.5 · chi2=20 · Actual n=4 · x_w=5 · u_w=0.5 · chi2=20 · nu=3 · birge=2.581988897471611
`boundary-wm-one`	boundary	pass	Expected x_w=5 · u_w=2 · chi2=0 · Actual n=1 · x_w=5 · u_w=2 · chi2=0 · nu=0
`boundary-wm-len`	boundary	pass	Expected INVALID_INPUT · Actual INVALID_INPUT
`boundary-wm-missing`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`boundary-wm-zero`	boundary	pass	Expected VALUE_MUST_BE_POSITIVE · Actual VALUE_MUST_BE_POSITIVE
`property-wm`	property	pass	5
`property-wm-not-rss`	property	pass	0.5≠2
`property-wm-one`	property	pass	5