Interlaboratory comparisons (ILC) or Proficiency Tests (PT) are based on testing the same samples by different calibration/testing laboratories and comparing the results.
This is a requirement for laboratories accredited according to the TS EN ISO/IEC 17025 standard.
Multitech Technology organizes inter-laboratory comparisons, enabling participants to conduct comparative experiments using reference experimental samples.
The application consists of the following steps:
- Proficiency Tests are organized by Multitech Technology based on requests from approved or accredited laboratories.
- As many participants as possible are reached and the necessary experimental samples are sent.
- Participants perform the specified experiments on the provided reference samples and record the results.
- The values submitted by the participants are compared against reference values that are either predetermined or calculated later based on the participants’ own findings.
- Finally, participants are sent a report indicating their deviations from the reference values, possible causes of the deviations, and possible corrective and preventive actions.
To maximize the benefits of the Proficiency Tests and understand the reasons for any deviations, participants must provide accurate answers to questions regarding both laboratory conditions and experimental methods.
Furthermore, a participant’s information or results are never shared with other participants, and the entire process is conducted with the utmost care.
Reliability of Proficiency Tests
If the tests carried out by your laboratories are used to check the quality of your products or processes, or to ensure compliance with regulations, any errors in these checks can have very serious consequences.
For an independent laboratory, unreliable test results damage its reputation and the trust of its clients. In any case, client trust is undermined, the organization’s reputation is damaged, and inappropriate calculations and results lead to additional costs.
The main reasons for participating in Proficiency Tests are also listed below.
- An error in test results can have serious consequences and cause financial losses for companies.
- Participating in a Proficiency Test is a very effective method for assessing competence in a laboratory and is required for TS EN ISO/IEC 17025 accreditation.
- It helps to find uncertainties in test results and to evaluate the results.
- Participants need to know the reliability of the test results.
- You also need to demonstrate to your clients that your test results are reliable.
- Finally, the cost and benefits of Proficiency Testing far outweigh the drawbacks of unreliable test results.
Using the Results of Proficiency Tests
The ISO/IEC 17043 and ISO 13528 standards, which address Proficiency Testing to assess the competence of laboratories, state that anomalous test results can be obtained even by laboratories with experienced personnel.
Therefore, the results of a Proficiency Test should not be used to condemn a participant. They should be used to investigate the causes of possible deviations and, if necessary, to take corrective and preventive actions.
Reliability of Proficiency Test Assessments
The reliability of evaluating a laboratory’s performance through Proficiency Testing depends on the following conditions:
- Stability and homogeneity of the samples used.
- The adequacy and robustness of the statistics used regarding technical issues related to test methods and participant numbers;
- Potential staffing impacts, particularly the improper rounding of results;
- Where applicable, a method for accounting for uncertainty measurement.
The main scope of ISO/IEC 17043 and ISO 13528 standards is to ensure the reliability of assessments made through inter-laboratory comparisons.
In particular, issues of sample stability and homogeneity, as well as the adequacy of statistical methods, have been extensively improved. A proper assessment of performance is clearly impossible if the samples used are not sufficiently similar or if inappropriate statistical methods are employed.
For more details on this topic, please review the summary of ISO 13528.
Meeting the requirements of ISO/IEC 17043 and ISO 13528 standards guarantees the elimination of the risk of unreliability associated with operations carried out by the Proficiency Testing Provider.
However, it should not be forgotten that the conditions under which data and results are prepared are as important as the statistical methods themselves and must be taken into account. Some of the most important things you need to check are:
- Human influences
- Other environmental factors taken into account.
A significant example of the importance of other environmental factors is the conditioning procedure for test samples, which significantly affects test results.
In these cases, the Proficiency Tests Provider sometimes makes the decision themselves and sometimes leaves it to the participant’s discretion regarding the technical aspects of the product, the test procedure, and the preparation and conditioning of the test samples.