Do laboratories have to conduct capability testing?

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I. What is proficiency testing? Proficiency testing refers to the activity of using inter-laboratory comparisons to determine a laboratory’s testing/calibration capabilities. It is a verification activity that assesses, monitors, and confirms a laboratory’s capabilities in order to ensure that it maintains high levels of calibration and testing. Participating in proficiency testing programs can provide laboratories with objective evidence to assess the reliability and validity of the data they generate. II. Under what circumstances is proficiency testing necessary? Requirement 4.2.3 of the CNAS-RL02 criteria regarding proficiency testing states that, whenever such testing is available, each sub-area for which a certification body applies for recognition for the first time must have participated in at least one proficiency test and achieved satisfactory results (proficiency tests conducted within 3 years prior to the date of application for recognition are valid). The division of sub-domains and the requirements regarding frequency must comply with the table of proficiency testing domains and frequencies published by CNAS. 4.2.4 As long as capability testing is available, accredited conformity assessment bodies shall meet the CNAS requirements regarding the areas and frequency of such testing and obtain satisfactory results. For areas (sub-areas) not listed in the CNAS proficiency testing areas and frequency table, as long as there are available proficiency tests, accredited conformity assessment bodies are required to participate in at least one such test per accreditation cycle. From a regulatory perspective, whether it is an accredited laboratory or one applying for accreditation for the first time, it is necessary to actively participate in proficiency testing. III. The significance of proficiency testing: Laboratories and testing agencies can use proficiency testing, an external quality assurance (EQA) tool, to identify differences with peer institutions, complement their internal quality control methods, and obtain information for their own continuous improvement and quality management ； Users of laboratories, supervisory and management agencies, evaluation bodies, etc., can use the CNAS proficiency testing results to determine whether laboratories and testing institutions possess the capability to carry out calibration/inspection activities, as well as to monitor the ongoing status of their capabilities. The specific manifestations are as follows: 1. Identifying differences between laboratories – Capability verification involves independently evaluating a laboratory’s performance in carrying out certain testing, calibration, and inspection activities by comparing the results obtained by that laboratory with specified values, thereby identifying the differences between the laboratory’s results and reference values, as well as among different laboratories. Capability testing can provide early warnings as to whether the quality or level of a laboratory’s work is satisfactory and whether it is necessary to investigate potential problems. 2. For some laboratories, comparative methods or procedures can be used to assess the quality of testing/measurement work conducted by those laboratories using a new or unconventional method, through proficiency testing. In some cases, proficiency testing programs provide a summary and comparison of the methods used by all laboratories. For new or infrequently conducted measurement activities in a laboratory, such data can be extremely valuable; it can help the laboratory choose appropriate methods in the future or indicate additional research that needs to be carried out before adopting new methods. 3. Verify that the measurement uncertainty claimed by the laboratory is included in the calibration proficiency testing program; proficiency testing can help assess the validity of the measurement uncertainty evaluated by the laboratory. If its measured value falls outside the acceptable range, it indicates that the laboratory fails to achieve the claimed measurement uncertainty; this may be due to an unreasonable assessment of the measurement uncertainty by the laboratory. 4. There are many tools for personnel training; proficiency testing programs provide information on methods, data interpretation, uncertainty assessment, and other aspects based on their overall results. For laboratory operators, some proficiency testing programs offer comprehensive training functions. In certain proficiency testing programs, when sufficient and stable proficiency testing materials are available, laboratories can use the unused/reusable proficiency testing materials as quality control samples to monitor their own capabilities. Items for verifying capabilities such as standby power consumption in the electrical field are retained in the laboratory as quality control samples. Where appropriate, the specified values of proficiency testing materials can be used as reference values for internal quality control activities such as testing, calibration, and staff training, thereby providing additional benefits to the laboratory by allowing comparisons of the differences in results among different personnel. 5. The tool proficiency testing for risk management and quality improvement can help laboratories identify potential problems. In proficiency testing, if there is a significant discrepancy between the laboratory’s results and the specified values or other criteria for assessing competence, the laboratory should investigate the potential sources of error or unsatisfactory results, identify the problems, and initiate corrective and preventive actions. These issues may be related to factors such as inappropriate testing or measurement procedures, staff training and the effectiveness of supervision, and instrument calibration. If proficiency testing is not conducted, the laboratory may fail to identify these sources of error and thus be unable to take appropriate corrective actions. Consequently, the laboratory may continue to provide suspicious or incorrect results to stakeholders such as customers. Finally, these errors may damage the reputation of the laboratory. Therefore, it is crucial for laboratories to use participation in proficiency testing as a tool for risk management and quality improvement. III. What is included in a proficiency testing report? A proficiency testing report contains information on the results of all participants, indicating each participant’s competence. It usually includes the following: 1) The name and detailed contact information of the proficiency testing provider ； 2) Name and detailed contact information of the proficiency testing coordinator ； 3) Name, position, signature, or equivalent identification of the person who approved the proficiency testing report ； 4) Explanation of the subcontracting activities of the proficiency testing provider ； 5) Date of issuance and status of the proficiency testing report (interim and final reports) ； 6) Page numbers of the proficiency testing report and a clear end marker ； 7) Statement on the level of confidentiality of proficiency testing results ； 8) Number and clear identification of the proficiency testing plan report ； 9) A clear description of the proficiency testing materials, including the necessary details for the preparation of these materials as well as the assessment of their uniformity and stability ； 10) Results of proficiency test participants ； 11) Proficiency testing statistical data and result statistics, including specified values, acceptable result ranges, and graphical representations ； 12) Procedures for using proficiency testing to determine specified values ； 13) Detailed information on the metrological traceability of the specified value and measurement uncertainty ； 14) Methods for determining the standard deviation of capability assessment or other evaluation criteria ； 15) The specified values and result statistics corresponding to the testing methods/procedures used in the laboratory for each group (if participants in different groups used different methods) ； 16) Comments on participants’ capabilities by proficiency testing providers and technical advisors ； 17) Information on the design and implementation of proficiency testing programs ； 18) Methods of data statistical analysis ； 19) Suggestions for interpreting statistical analysis ； 20) Comments or recommendations based on the results of this round of capability verification. IV. How to interpret proficiency testing reports: Upon receiving a proficiency testing report, one should not focus solely on whether the test results are satisfactory; instead, it is necessary to extract as much useful information as possible from the report, such as understanding the differences between various measurement methods, as well as the technical analyses and recommendations provided by the testing organization. (1) When a laboratory obtains unsatisfactory results in capacity verification and can no longer meet the criteria specified in the standards or regulations governing the accredited programs, it shall suspend the use of the CNAS accreditation mark on the certificates/reports related to those programs. It must also take appropriate corrective actions in accordance with the provisions of its laboratory’s system documents, and verify the effectiveness of such corrective actions. After verifying the effectiveness of the corrective actions, the laboratory resumed using the accreditation mark on its own. The laboratory’s corrective actions and verification activities (where feasible) shall be completed within 180 days (starting from the date of issuance of the proficiency testing final report). The laboratory shall keep the above records for inspection by the review team. Methods for verifying the effectiveness of corrective actions: participating in proficiency testing activities again or undergoing on-site evaluation by the CNAS review team. (II) When the results of laboratory proficiency testing are suspicious or problematic, a risk assessment should be conducted for the relevant items, and preventive or corrective measures should be taken if necessary. Analyze the reasons for dissatisfaction or suspicion: (1) Typos and technical issues. Typographical errors such as transcription mistakes, incorrect labels, decimal point errors, etc. (2) Technical reasons such as improper storage or pretreatment of samples, issues with the measurement methods or internal quality control, abnormalities in standards, poor condition of equipment, unsuitable environmental conditions, or problems with data processing. In some cases: for example, when using the participants’ results to determine the standard deviation for ability assessment, if the overall level of the participants is very consistent or if collusion results in a low standard deviation for ability assessment, causing certain participants’ results to trigger warning or action signals, the participants can contact the organizing agency to find out the reasons for these outliers, and they can suggest that the agency use a more appropriate standard deviation for ability assessment. If there are judgment requirements specified in the testing method standards or specifications, and the test results fall within the acceptable range set by those standards or specifications, then even if the results are atypical, they can still be considered satisfactory; the participants can make a reasonable assessment of the results without the need to take any further corrective actions. (III) When participants are unsatisfied with the results or have doubts, the common corrective measures taken include verifying whether the relevant personnel understand and follow the measurement procedures ； Verify that all details of the measurement procedure are correct ； Verify equipment calibration and the composition of reagents ； Replace the suspicious equipment or reagents ； Conduct comparative tests for personnel, equipment, and/or reagents with personnel from another laboratory.