IJCA Vol 5 Issue 1 - Flipbook - Page 46
The International Journal of Conformity Assessment
8. Use of PT and ILC Results for Continual
Improvement
Beyond their role in demonstrating compliance
with accreditation requirements, proficiency
testing and interlaboratory comparison results
provide valuable input for continual improvement
within calibration laboratories. When reviewed and
used systematically, PT and ILC outcomes support
technical decision-making, reinforce confidence
in measurement results, and contribute to the
ongoing evaluation of laboratory competence.
ISO/IEC 17025 requires laboratories not only to
participate in appropriate comparison activities,
but also to evaluate results and take action
when performance is unsatisfactory. ILAC-P9
reinforces this expectation by emphasizing that
PT and ILC participation should be embedded
within a broader, risk-based quality management
framework. The value of these activities is
therefore realized through interpretation, follow-up,
and integration into routine quality processes.
2026 | Volume 5, Issue 1
results. Incorporating trend analysis into
routine quality activities supports proactive risk
management and aligns with the intent of riskbased thinking in ISO/IEC 17025 and ILAC-P9.
8.3 Integration with Management Review and Risk
Assessment
PT and ILC outcomes should be reviewed as part
of the laboratory’s management review process,
alongside other indicators of performance and
risk. This integration ensures that comparison
results inform strategic decisions related to scope,
resources, training, equipment maintenance, and
uncertainty budgets.
By linking PT and ILC results to risk assessment,
laboratories can adjust participation strategies,
refine measurement capabilities, and prioritize
improvement actions. This approach reinforces
the role of PT and ILC activities as tools for
continual improvement rather than isolated
compliance exercises.
8.1 Interpretation of Results and Corrective Action
8.4 Supporting Confidence in Measurement
Results
When PT or ILC results indicate unsatisfactory
performance, laboratories are expected to initiate
investigation and corrective action in accordance
with their quality management procedures. This
process may involve review of measurement
methods, reference standards, environmental
conditions, personnel competence, or uncertainty
estimation. Corrective actions should be
proportionate to the identified risk and supported
by documented evidence.
When PT and ILC participation is planned
strategically, evaluated appropriately, and
integrated into quality management activities,
comparison outcomes strengthen confidence in
reported calibration results. By demonstrating
consistency, compatibility, and transparency
in measurement performance, laboratories
provide assurance to customers, regulators, and
accreditation bodies that results are technically
valid and reliable.
Even when results are satisfactory, laboratories
may identify opportunities for improvement.
Marginal results, emerging trends, or
inconsistencies across similar activities
may warrant additional review. In calibration
contexts, particular attention is often given to the
consistency between reported uncertainties and
observed performance.
9. Conclusion
8.2 Trend Analysis and Longitudinal Review
Individual comparison results provide limited
insight into long-term performance. When reviewed
collectively over time, however, PT and ILC outcomes
can reveal trends that may not be apparent from
isolated events. Longitudinal review supports
identification of systematic bias, drift, or instability in
measurement processes or reference standards.
Tracking performance indicators across multiple
comparison rounds enables laboratories to assess
the robustness and consistency of measurement
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Recent revisions to ISO/IEC 17043:2023 and
ILAC-P9:01/2024 reinforce the central role
of proficiency testing and interlaboratory
comparisons in demonstrating and maintaining
competence in calibration laboratories. These
updates place increased emphasis on structured
planning, technical justification, and informed
interpretation of results, moving PT and ILC
participation beyond periodic compliance
activities toward integrated elements of laboratory
risk management and quality assurance.
For calibration laboratories, the implications
are multifaceted. Clear distinction between PT
and other forms of ILC is essential for meeting
accreditation requirements and avoiding
misinterpretation of comparison activities.
Risk-based participation planning, supported by
documented justification and periodic review,
