Expert View - August 2025
Interlaboratory or Intralaboratory? How Labs Show True Competence!
By Dr. George Anastasopoulos
Technical & Intl. Business Development Mgr., PJLA
I recently received the following question from a calibration laboratory: “We would like to request clarification regarding the distinction between interlaboratory and intralaboratory programs in the context of ISO/IEC 17025 compliance. Specifically, we seek confirmation on whether both types of programs are considered acceptable evidence of ongoing competence for the purposes of maintaining accreditation.”
First, I would like to note that this question is also valid for a testing laboratory. So my reply is applicable to both Testing and Calibration laboratories:
An interlaboratory program, often referred to as an interlaboratory comparison (ILC), involves two or more independent laboratories measuring the same or similar items under predetermined conditions and comparing the results.
Its primary purpose is to evaluate comparability between laboratories. It can be performed in a more formal process through proficiency testing (PT) organized by an external provider.
ILC’s are performed according an interlaboratory protocol, a documented set of standardized instructions defining how an interlaboratory comparison or proficiency testing exercise will be conducted, including the purpose, scope, participant requirements, sample handling, test methods, data reporting, statistical analysis, confidentiality, and reporting procedures, ensuring all participants follow consistent conditions for valid and comparable results.
In interlaboratory comparisons, statistical z-scores or performance ratings are used to benchmark a laboratory’s results against those of other participants, providing an objective measure of performance and identifying deviations from the assigned reference value. They are numerical indicators to show how a laboratory’s result compares to the overall group. A z-score tells you how many “standard deviations” your result is from the accepted value.
Usually when:
- |z| ≤ 2 → Satisfactory result (within normal variation)
- 2 < |z| < 3 → Questionable result (possible issue to investigate)
- |z| ≥ 3 → Unsatisfactory result (significant deviation)
In contrast, an intralaboratory program, or intralaboratory comparison, is carried out within a single laboratory, where different analysts, instruments, or methods are used to measure the same or similar items under controlled conditions. This is intended to verify internal consistency and assess the repeatability and reproducibility of results within that laboratory.
In intralaboratory comparisons, internal control charts are graphical tools used to monitor measurement results over time, helping detect trends, shifts, or out-of-control conditions within the same laboratory. Repeatability data measures the variation when the same operator, equipment, and method are used under identical conditions over a short time, while reproducibility data measures the variation when different operators, equipment, or conditions within the same lab perform the same test.
Together, these tools provide ongoing evidence of internal consistency, method stability, and staff competence.
For accreditation purposes, particularly under ISO/IEC 17025, the distinction matters because the two approaches address different but complementary aspects of competence.
Interlaboratory comparisons provide objective evidence of performance against external peers, help detect systematic bias, and are often required when formal PT is available, as referenced in ISO/IEC 17025:2017 clause 7.7.2 and ILAC P9:01/2024 “ILAC Policy for Proficiency Testing and/or Interlaboratory comparisons other than Proficiency Testing”.
Intralaboratory comparisons, on the other hand, serve as an ongoing internal quality control tool, supporting the monitoring of methods, personnel, and equipment performance in accordance with clause 7.7.1.
Accreditation bodies expect laboratories to demonstrate both types of evidence—interlaboratory programs to confirm traceability and external comparability, and intralaboratory programs to prove active internal quality assurance practices.
Using only intralaboratory checks risks masking biases, while relying solely on interlaboratory PT may overlook day-to-day operational issues.
A balanced approach ensures continuous verification of competence, strengthens measurement assurance, and reduces the likelihood of nonconformities during accreditation assessments.
I hope this helps!
Disclaimer: The above recommendations are offered solely as examples of good practice and do not constitute formal advice or assurance for achieving or maintaining accreditation.
About the Author
Dr. George Anastasopoulos is the Technical and International Business Development Manager at Perry Johnson Laboratory Accreditation, Inc.(PJLA), a leading U.S.-based accreditation body operating globally across multiple technical and scientific sectors. He also serves as General Secretary of the International Personnel Certification Association (IPC).
A Mechanical Engineer with an MSc and PhD in Applied Mechanics from Northwestern University, Dr. Anastasopoulos is an active member of several international standards committees, including ISO/TC 176, ISO/CASCO, and ASTM, contributing to the development of ISO 9001 and ISO/IEC 17025. He is also a regular participant in IAF and ILAC global accreditation activities.
He has received the EOQ Presidential Georges Borel Award for his international achievements in promoting quality worldwide and has published extensively in journals and conferences. As a keynote speaker and project leader, he has contributed to numerous initiatives in conformity assessment, management systems, and quality assurance across the U.S., EU, and beyond. He can be contacted at ganast@pjlabs.com
Expert View - July 2025
Competence vs. Qualification in Personnel Certification
By Dr. George Anastasopoulos
Technical & Intl. Business Development Mgr., PJLA
In today’s highly competitive and ever-evolving professional landscape, personnel certification remains a valuable asset for individuals seeking to demonstrate their abilities and advance their careers. Obtaining a professional certification often requires a significant investment of time, effort, and financial resources. For this reason, candidates are increasingly faced with a critical choice: whether to pursue a competence-based or a qualification-based certification program.
At first glance, qualification-based certification may seem more accessible. It is often easier to obtain, less expensive, and focused primarily on formal education or training history. However, this convenience may come at the cost of genuine credibility and market acceptance. So, what really distinguishes competence-based from qualification-based certification, and which one truly holds value in today’s global market?
Definitions That Matter
According to ISO 19011, Guidelines for Auditing Management Systems, competence is defined as “the ability to apply knowledge and skills to achieve intended results.” In practical terms, competence-based certification requires candidates to demonstrate their abilities through validated means - such as examinations, practical assessments, or performance evaluations - covering not only knowledge, but also skills and behaviors aligned with the certification’s scope.
On the other hand, qualification-based certification typically relies on reviewing the applicant’s education, course attendance, or prior training. It assumes that completion of training equals capability, with minimal or no independent verification of actual performance or ability.
Consider the following simple yet illustrative exchange:
- "Do you know how to drive a car?"
- "I’ve taken lessons, and I have a license, but I’m still not confident behind the wheel."
- "Then you have the qualifications, but not the competence."
This brief dialogue captures a critical truth: Qualifications alone do not guarantee competence. History is filled with examples of individuals - college dropouts among them - who rose to executive leadership roles not because of their academic records, but because of their demonstrated competence.
ISO/IEC 17024: Setting the Global Standard
Recognizing this distinction, the International Organization for Standardization (ISO) developed ISO/IEC 17024, “Conformity assessment – General requirements for bodies operating certification of persons”. This international standard outlines how Personnel Certification Bodies (PCBs) should operate to ensure fairness, consistency, and - most importantly - validity in how certifications are awarded.
ISO/IEC 17024 mandates that certifications must be based on demonstrated competence, not just possession of qualifications. The standard provides a comprehensive framework for assessing competence through valid, reliable, and impartial examinations, practical tests, or other evaluation methods. While it allows flexibility in assessment methods, its core principle is clear: competence must be measurable, observable, and independently verified.
This approach has been widely adopted by businesses, industries, regulators, and governments worldwide as the most reliable way to ensure that certified professionals truly meet the expectations of their roles.
The Pitfall of Qualification-Based Certifications
Despite the growing emphasis on competence, some certification bodies continue to offer non-accredited, qualification-based programs. These programs often assume that a person’s educational background is a sufficient indicator of capability. While this may occasionally be true - especially in academic or theoretical fields - it falls short in professions where actual performance, judgment, and applied skill are critical.
Such programs contribute to confusion among employers, regulators, and candidates. More importantly, qualification-based programs cannot be accredited under ISO/IEC 17024, since they do not meet its requirements for competence assessment. As a result, they offer limited value in environments that demand objective proof of ability.
Training vs. Assessment: The Shift in Focus
A key distinction between the two approaches lies in their emphasis. Qualification-based certification often focuses on the completion of training programs. If you've attended a course, you may receive a certificate, regardless of how well you've mastered the material.
In contrast, competence-based certification starts by defining the required competencies and then verifying whether the candidate has achieved them, typically through structured, independent assessments. The goal is not to reward participation, but to validate actual ability.
In competence-based systems, training is important, but it is not enough. The real emphasis is on the results of training, measured through robust and impartial evaluation.
How to Recognize a Competence-Based Certification Program
So, how can one tell whether a certification program is truly competence-based? Here is a simple checklist:
- Accreditation to ISO/IEC 17024: Verify that the PCB is accredited to this standard.
- Program Scope: Check that the specific certification program is included in the PCB’s accredited scope.
- Credible Accreditation Body: Ensure that the accreditation has been granted by a body that is a signatory to the International Accreditation Forum (IAF) Multilateral Recognition Arrangement (MLA) and/or is an MLA signatory of the International Personnel Certification Association (IPC). Visit www.iaf.nu or www.ipcaweb.org to verify membership and recognition.
Accreditation under these arrangements provides assurance that the certification process meets internationally accepted best practices.
Conclusion: Competence Is the Currency of Trust
In summary, while both types of certifications may serve specific purposes, competence-based certification carries significantly greater weight in professional, technical, and regulated environments. It offers a more rigorous, transparent, and trustworthy validation of a person’s abilities, providing assurance not only to employers and clients, but also to the certified professionals themselves.
In a world where performance matters more than paperwork, competence is the true currency of professional credibility. Before investing in any certification, professionals and organizations alike should ask: Does this program prove what I can do or just what I’ve done?
About the Author
Dr. George Anastasopoulos is the Technical and International Business Development Manager at Perry Johnson Laboratory Accreditation, Inc.(PJLA), a leading U.S.-based accreditation body operating globally across multiple technical and scientific sectors. He also serves as General Secretary of the International Personnel Certification Association (IPC).
A Mechanical Engineer with an MSc and PhD in Applied Mechanics from Northwestern University, Dr. Anastasopoulos is an active member of several international standards committees, including ISO/TC 176, ISO/CASCO, and ASTM, contributing to the development of ISO 9001 and ISO/IEC 17025. He is also a regular participant in IAF and ILAC global accreditation activities.
He has received the EOQ Presidential Georges Borel Award for his international achievements in promoting quality worldwide and has published extensively in journals and conferences. As a keynote speaker and project leader, he has contributed to numerous initiatives in conformity assessment, management systems, and quality assurance across the U.S., EU, and beyond. He can be contacted at ganast@pjlabs.com