Proficiency Testing Programs (PT) are an essential tool for demonstrating the technical competence of laboratories performing testing, analysis, or calibration activities. In regulated environments, where the reliability of analytical results is critical for decision-making, interlaboratory comparison schemes allow for an objective evaluation of a laboratory’s performance in relation to other participants applying the same method.
In sectors such as biocides, cosmetics, disinfectants, microbiology, and efficacy testing, Proficiency Testing Programs are not merely a good practice, but a key element within quality systems based on international standards.
What Is A Proficiency Testing Program
A Proficiency Testing Program is an external evaluation exercise in which several laboratories analyse the same sample or set of samples following a defined method. The results obtained are statistically compared with an assigned value or with the group consensus, allowing the individual performance of each laboratory to be assessed.
The main objective of these programs is to determine whether a laboratory is capable of producing technically valid, reproducible, and comparable results, under controlled conditions and using defined acceptance criteria.
Proficiency Testing Programs are designed to:
- Assess technical competence
- Detect systematic or random deviations
- Identify opportunities for improvement
- Provide objective evidence for audits
Regulatory Framework And Relationship With ISO/IEC 17025 And ISO/IEC 17043
Proficiency testing is closely linked to laboratory quality management systems.
This standard, applicable to testing and calibration laboratories, establishes that laboratories must ensure the validity of their results, which includes:
- Participation in proficiency testing
- Interlaboratory comparisons
- Use of external quality control measures
Regular participation in Proficiency Testing Programs is one of the most highly valued forms of evidence during accreditation audits.
This standard defines the requirements for proficiency testing providers, ensuring that programs are designed, implemented, and evaluated in a technically competent, impartial, and traceable manner.
A reliable Proficiency Testing Program must be aligned with ISO/IEC 17043 to ensure the validity of results and the confidence of participants.
Data Analysis In Proficiency Testing Programs
Statistical analysis of results is one of the most critical elements of any Proficiency Testing Program, as it determines how the performance of participating laboratories is interpreted.
This phase relies on specific standards and guidelines that provide the methodological framework for data evaluation.
ISO 5725: Accuracy And Precision Of Results
The ISO 5725 standard establishes the principles for evaluating the accuracy of a measurement method, breaking it down into:
- Trueness: closeness of the mean value to the reference value
- Precision: dispersion of results among laboratories
In the context of Proficiency Testing Programs, ISO 5725 is used as a reference to analyse the repeatability and reproducibility of the results obtained, enabling the identification of excessive variability or systematic bias among participants.
ISO/IEC Guide 35: Assignment Of The Reference Value
ISO/IEC Guide 35 provides guidance on:
- Assignment of the reference value
- Evaluation of the associated uncertainty
- Verification of sample homogeneity and stability
This guide is particularly relevant when the assigned value is not theoretical but is obtained through statistical methods or by consensus among participants, ensuring traceability and robustness of the evaluation process.
Why Proficiency Testing Programs Are Used
Proficiency testing fulfils multiple functions within a laboratory:
- Verifying the technical competence of personnel
- Confirming the correct application of the method
- Evaluating equipment, reagents, and procedures
- Detecting errors before they affect real results
- Demonstrating compliance to accreditation bodies
In addition, these programs allow laboratories to compare their own performance with that of other laboratories in the same sector, providing an objective view of their technical level.
How A Proficiency Testing Program Works
Although the design may vary depending on the type of test, a Proficiency Testing Program generally follows the same stages:
Program Design
Definition of:
- Objective of the test
- Method or reference standard used
- Sample type involved
- Number of participating laboratories
- Statistical criteria applied for evaluation
Sample Preparation And Distribution
Samples must be:
- Homogeneous
- Stable throughout the program
- Representative of the actual test
They are sent to participants together with clear instructions.
Analysis Performed By The Laboratories
Each laboratory analyses the sample:
- Using its routine method
- Under its normal working conditions
- Without knowledge of the results of other participants
Collection And Evaluation Of Results
Results are collected and subjected to statistical analysis in order to:
- Compare individual results
- Identify deviations
- Calculate performance indicators
Final Report
The program provider issues a report that includes:
- Individual results
- Statistical evaluation
- Performance interpretation
- Technical observations
This report constitutes key evidence for audits and internal reviews.
Types Of Proficiency Testing Programs
Proficiency Testing Programs can be adapted to different technical needs:
- Quantitative: comparable numerical results
- Qualitative: presence/absence, positive/negative
- Microbiological: counts, efficacy, identification
- Efficacy testing: bactericidal, fungicidal, virucidal, sporicidal
- Programs specific to standards (EN, ISO, etc.)
The choice of program must be aligned with the technical scope of the laboratory.
Direct Benefits For Laboratories
Regular participation in Proficiency Testing Programs provides clear benefits:
- Continuous quality improvement
- Reduction of analytical risks
- Increased confidence in results
- Better preparation for audits
- Early detection of deviations
- Strengthened credibility with clients and authorities
The goal is not simply to “pass” a test, but to use the results as a tool for improvement.
Proficiency Testing Programs In Regulated Sectors
In highly regulated sectors such as:
- Biocides
- Cosmetics
- Disinfectants
- Medical products
- Microbiological control
Proficiency Testing Programs play a particularly important role, as analytical results may have a direct impact on safety, legal compliance, and product marketing.
Interpretation Of Results And Deviation Management
An unsatisfactory result in a Proficiency Testing Program should not be interpreted as a failure, but as an opportunity for improvement.
In the event of a deviation, the laboratory should:
- Analyse root causes
- Review methods and equipment
- Assess staff training
- Implement corrective actions
- Document the process
This approach is fully aligned with quality management system requirements.
The SHAPYPRO Approach To Proficiency Testing Programs
The Proficiency Testing Programs developed by SHAPYPRO are designed to address the real needs of laboratories operating in regulated environments.
Their approach is based on:
- Programs aligned with European and international standards
- Representative and technically robust samples
- Transparent statistical evaluation
- Clear reports suitable for audits
- Technical support throughout the process
This model enables laboratories not only to meet regulatory requirements, but also to continuously improve their technical competence.
Conclusion: The Value Of Proficiency Testing Programs
Proficiency Testing Programs are an indispensable tool for ensuring the reliability, traceability, and credibility of analytical results. In a context where data quality is increasingly demanded by authorities, clients, and accreditation bodies, regular participation in proficiency testing represents a direct investment in laboratory excellence.
Beyond regulatory compliance, Proficiency Testing Programs allow laboratories to understand their own performance, improve their processes, and objectively demonstrate their competence within a controlled comparative environment.