Proficiency Testing — Glass Scale(Interlaboratory Comparison — Line Standard Comparison)
ISO/IEC 17043-aligned proficiency testing scheme for glass scale (line standard) calibration — circulated reference artefacts, ISO 13528 statistical evaluation (En / z-scores), and confidential performance reports for NABL-accredited and aspiring calibration laboratories.
What is the Proficiency Testing — Glass Scale Scheme?
Under ISO/IEC 17025:2017 (clause 7.7), every accredited calibration laboratory must monitor the validity of its results by participating in proficiency testing (PT) — and NABL expects documented, satisfactory PT participation across the accredited scope. Global Lab operates an ISO/IEC 17043:2023-aligned interlaboratory comparison scheme for glass scale (line standard) calibration: a characterised artefact travels between participating labs, each calibrates it by their normal method, and results are evaluated statistically against the assigned reference value.
Glass scales calibrate the projectors and microscopes that calibrate everything else — line-standard PT closes the loop on optical length traceability. The scheme measurand covers calibration of graduated glass scales by optical comparison, with results reported at defined graduation intervals across the scale length. Each participant receives a confidential performance report — En numbers and z-scores per ISO 13528 — through our Live PT Program portal, with anonymised group statistics and corrective-action guidance where performance flags arise.
How the Proficiency Testing — Glass Scale is Conducted
- 1
Enrolment
The laboratory enrols for the glass scale (line standard) scheme round through the Live PT Program portal and receives the scheme protocol. - 2
Artefact Receipt
The characterised artefact arrives per the circulation schedule with handling instructions and condition-check requirements. - 3
Calibration by Your Method
Your lab calibrates the circulated glass scale's defined intervals by its normal optical comparison method and reports deviations with uncertainties. - 4
Result Submission
Results with claimed uncertainties are submitted through the portal by the round deadline. - 5
Statistical Evaluation
Submissions are evaluated against the assigned value per ISO 13528 — En numbers and z-scores computed per measurement point. - 6
Performance Report
A confidential report with your performance flags and anonymised group statistics is issued; corrective-action guidance follows any unsatisfactory result.
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| ISO/IEC 17043:2023 | Conformity Assessment — General Requirements for the Competence of Proficiency Testing Providers | PT Scheme Operation | International |
| ISO 13528:2022 | Statistical Methods for Use in Proficiency Testing by Interlaboratory Comparison | En / z-Score Evaluation | International |
| ISO/IEC 17025:2017 | Competence of Testing and Calibration Laboratories (Clause 7.7) | Participation Requirement | International |