Public evidence

engineering.conformity.z_prime

Machine-checked verification for calculation version 1.0.0 · tier engine_tested

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Verification

12/12 calculation tests · Production surface contract 4/4

Golden tests 0 / 0
Boundary tests 7 / 7
Property tests 5 / 5
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Production attestation Embedded snapshot: unpublished · Build schema 1.0.0 ready · Semantic contract ✓ · Attestation report not published on origin · Live production status STALE (1 capability; 156 remain CURRENT)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 sha256:8a4146e0f033dbfb0eeeb257bb898223288c8ec0d6d473d545e42ccd393f5b0a

Input schema sha256:be3f4a7a23a15b3cfc3dbcc785be59c1aaa82852166c4e6172b842e0f500196f · Output schema sha256:8a7f4a4847ea8e046d38521484c7a62fbb0652af47899bb055e60464450d788c · 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: z-prime
Engine: z-prime
Engine build: 2026-09-15
Evidence core: 2026-09-15T23:04:28.329Z
Rendered: 2026-09-15T23:38:12.907Z
Last reviewed: —

Assumptions

ISO 13528 z′ = (ylab−xref)/√(σ_pt²+u(x_pt)²)
σ_pt > 0 and u(x_pt) > 0 — u(x_pt)=0 is not a z-score wrap
Not z-score, not zeta, and not En

Limitations

Requires σ_pt > 0 and u(x_pt) > 0 — this page does not wrap z-score
Not the z-score (that divides by σ_pt alone)
Not the zeta-score (that uses √(ulab²+uref²))
Not the normalized error En (that uses already-expanded U)
Not TUR and not an ILAC G8 specification decision on y

Sources

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

ISO 13528 — Statistical methods for use in proficiency testing by interlaboratory comparison — z′ score when the uncertainty of the assigned value is not negligible
Supports: z′ = (x − x_pt) / √(σ_pt² + u²(x_pt)). |z′| bands match the z-score bands.

Published checks

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

ID	Kind	Status	Detail
`boundary-zp`	boundary	pass	Expected z_prime=1 · abs_z_prime=1 · denom=5 · decision=pass · Actual z_prime=1 · abs_z_prime=1 · decision=pass · ylab=5 · xref=0 · sigma=3 · u_xref=4 · denom=5
`boundary-zp-two`	boundary	pass	Expected z_prime=2 · decision=pass · Actual z_prime=2 · abs_z_prime=2 · decision=pass · ylab=10 · xref=0 · sigma=3 · u_xref=4 · denom=5
`boundary-zp-warn`	boundary	pass	Expected z_prime=2.5 · decision=warning · Actual z_prime=2.5 · abs_z_prime=2.5 · decision=warning · ylab=12.5 · xref=0 · sigma=3 · u_xref=4 · denom=5
`boundary-zp-fail`	boundary	pass	Expected z_prime=3 · decision=fail · Actual z_prime=3 · abs_z_prime=3 · decision=fail · ylab=15 · xref=0 · sigma=3 · u_xref=4 · denom=5
`boundary-zp-missing`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`boundary-zp-u`	boundary	pass	Expected VALUE_MUST_BE_POSITIVE · Actual VALUE_MUST_BE_POSITIVE
`boundary-zp-ulab`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`property-zp`	property	pass	1
`property-zp-two`	property	pass	2
`property-zp-warn`	property	pass	warning
`property-zp-fail`	property	pass	fail
`property-zp-alias`	property	pass	1