OA05 PARTICIPATION IN INTERLABORATORY COMPARISONS. Table of contents

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1 PARTICIPATION IN INTERLABORATORY COMPARISONS Table of contents 1 GENERAL REQUIREMENTS ASSESSMENT INTERLABORATORY COMPARISONS IN SUPPORT OF MULTILATERAL AGREEMENTS EXPLANATIONS AND REMARKS CHANGES WITH REGARD TO PREVIOUS REVISION TRANSITORY PROVISIONS CONTROL OF THE DOCUMENT... 6 Revision 4 In use as of: Page 1 of 6

2 1 GENERAL 1.1 Interlaboratory comparison (ILC) means organisation, implementation and evaluation of the results of measurement and testing of the same or similar test items/samples carried out by two or more than two laboratories in conformity with pre-determined conditions. 1.2 The requirements for participation in interlaboratory comparisons are laid down in SIST EN ISO /IEC 17025, and they indirectly also apply to inspection bodies and certification bodies in relation with tests or calibrations which they conduct within their accredited procedures of inspection or certification (SIST EN ISO/IEC 17011). 1.3 Interlaboratory comparisons range among the most important tools used by a laboratory to monitor and control the quality of performance of its accredited activities and the results, and their comparability to the results of other laboratories active in the same field. The results of interlaboratory comparisons enable the identification of possible problems, and they are particularly important for verification of the laboratory's work when introducing changes or new activities. Successful participation in interlaboratory comparisons helps a laboratory to prove its competence, inter alia, to the accreditation body. The results of interlaboratory comparisons provide an important segment of assessment in accreditation procedures; however, they always cover a part of the laboratory's activities only, and can therefore never fully substitute an assessment (or surveillance) visit [3]. Interlaboratory comparisons between accredited bodies are also an indispensable means of establishing and ensuring equivalence of accreditation procedures within the framework of Multilateral Agreements (MLA) between accreditation bodies [4]. 1.4 Slovenian Accreditation shall encourage participation in ILCs and provide to ABs general information related to participation in ILCs, in particular invitations to participate in ILCs as referred to under REQUIREMENTS 2.1 Participation in appropriate interlaboratory comparisons, when available, is one of the conditions for a laboratory to obtain and maintain accreditation. When a laboratory needs to assure confidence in its results, it must regularly and to an appropriate extent take part in interlaboratory comparisons. In this context, the laboratory must have its policy stated, its plans made, and its procedures for processing the results and implementing the necessary action in place. Revision 4 In use as of: Page 2 of 6

3 2.2 Interlaboratory comparisons differ by their purpose, organisation, number of participants, etc. It is important for a laboratory to choose adequately, in compliance with its needs, and to make sure about the suitability of organisation, implementation and evaluation of the results (following the requirements under [7] or an equivalent document). Also in the case of comparison of results between laboratories, these should try to meet as much as possible the requirements for organisation of ILCs, and in interpreting the results of such comparison they should take into consideration the circumstances of implementation (e.g. non-fulfilment of individual requirements). 2.3 In line with the EA and ILAC policies, SA will require a laboratory's participation in interlaboratory comparisons at least once before the grant of accreditation, and subsequently, at least once during the period between reassessment visits (four years) in each of the larger sub-areas within the laboratory's scope of accreditation. 2.4 A laboratory shall plan the scope of its participation in ILCs in accordance with its accredited activity (capacity). 2.5 The requirement under 2.3 concerning the frequency of participation is a minimum requirement only. Many areas require much more frequent participation, whereas in other cases, for lack of organised comparisons, even this minimum requirement cannot be met. It is important, however, that the frequency of participation in interlaboratory comparisons is aligned with the scope of use of other means of assuring the quality of testing and calibration. (Guidance on defining the frequency of participation in ILCs is given in EA-4/18.) (Less frequent participation in interlaboratory comparisons, for example, may require more: equipment calibration, use of reference materials, repeated testing, control, and the like and vice versa.) 2.6 Under special circumstances (important changes in the laboratory, nonconformities found, extra critical tests or calibrations), SA may require the laboratory's participation in interlaboratory comparisons in shorter intervals. 2.7 A laboratory in accreditation procedure is required to test or calibrate a well characterised specimen/sample, which may be brought by the assessor or provided by a third party. This is also considered as a special form of (bilateral) inter-laboratory comparison. Revision 4 In use as of: Page 3 of 6

4 2.8 In order to attain the purpose of participation as a means of quality assurance, the laboratory needs to introduce procedures for examining the results, following the trends, deriving findings, as well as implementing and reviewing corrective and preventive actions. All these activities must be properly documented. 2.9 When an ILC organiser provides a reference value independent of measurements, the laboratory can most properly determine its success by taking into account its results and the estimated measurement uncertainty. (The adequate agreement between the measured value and the reference value shall be evaluated by a chosen fit-for-purpose statistical method, e.g. by calculation of E n value [7]). When the accepted value in ILC is determined from the results of the participants, the organiser will usually determine the success criterion. Each participating laboratory should check the criterion for meeting the conditions of use of its results. When the measurement uncertainty of the accepted value is determined, the laboratory can also determine its success against its specified measurement uncertainty. In each case the laboratory should also determine the adequacy of its estimate of measurement uncertainty of the result on the basis of the results of ILC; when the accepted value of ILC in several successive cycles lies outside the measurement uncertainty of the result, the laboratory may have underestimated the uncertainty of its results. 3 ASSESSMENT 3.1 The suitability of the scope of participation and the adequacy of chosen interlaboratory comparisons shall be estimated by the assessment team during the assessment procedure. Both the actual possibilities and situation in the relevant area should be taken into account. 3.2 The plan, the results, the analysis, as well as any possible actions deriving from the result of participation in ILCs, shall in accordance with the accreditation procedure constitute an obligatory part of review during each surveillance/assessment visit. When applying, and before each visit, the laboratory shall send its report on the quality control of testing and calibration results provided through its participation in ILCs or proficiency tests (PTs). (In exceptional cases, where participation in PT programmes is not possible, the laboratory shall report of other means used to ensure the quality of results, in line with the expectations of SIST EN ISO/IEC 17025, 5.9.) 3.3 Utmost attention should be paid when assessing a laboratory to checking its control of the results of participation in ILCs and the implementation of corrective actions in the case of derogations. Revision 4 In use as of: Page 4 of 6

5 A single inadequate result of participation in ILC should not necessarily mean nonconformity, provided that efficient corrective actions have been implemented and that other results for the same accredited activity are for the most part adequate. When the reason for a considerable derogation or recurrent derogations in the same or similar activities cannot be established, these should be considered as nonconformities for which the assessor team should require immediate action by the laboratory. Should the laboratory not take the appropriate corrective actions within an acceptable period of time, this could provide a reason for withdrawal or narrowing of the scope of accreditation. 3.4 When a laboratory's participation is unsuccessful, and the appropriate action has not been taken in proper time, or when a laboratory has unsuccessfully participated several times in a sequence, SA may: require another participation in a similar comparison; undertake an extraordinary surveillance visit; or withdraw partly or completely the laboratory's accreditation. 4 INTERLABORATORY COMPARISONS IN SUPPORT OF MULTILATERAL AGREEMENTS 4.1 The basic intention of ILCs initiated by EA (Regional ILCs) or some other regional association of accreditation bodies (e.g. ILCs organised by APLAC, "EA highlighted" PTs), is to determine equal competences of accredited bodies in order to verify the results of work of the accreditation bodies signatories to Multilateral Agreements (e.g. EA MLA) [4]. In some cases (especially in calibration laboratories) SA may partially evaluate the participation of a calibration laboratory through the results of ILC, already in the phase of preliminary results, immediately after the comparison. Such report alone will usually not suffice for actions concerning the accreditation status. In the case of negative results, SA will require of the laboratory to provide a report on the corrective actions taken, and will carry out regular or extraordinary surveillance to identify the circumstances. Only on the basis of this information, changes may also occur in the accreditation status (suspension or withdrawal, change of scope, narrowing of scope, ). 5 EXPLANATIONS AND REMARKS 5.1 The requirements stated above cannot apply to areas for which interlaboratory comparisons are not practicable. 5.2 Possibilities of participation in interlaboratory comparisons differ greatly by different areas. Laboratories should choose such comparisons that meet the requirements of international standards (e.g. [6]). When such comparisons are not available, or when a laboratory chooses for other reasons to take part in a comparison which does not meet the requirements, the laboratory must take this into account when evaluating its results. In the absence of interlaboratory comparisons organised by third parties, even comparisons between two or more than two laboratories, organised Revision 4 In use as of: Page 5 of 6

6 by the laboratories themselves, are welcome. Doing so, they should take the requirements of international standards into consideration as much as possible. 5.3 Special requirements for participation in ILCs in particular areas shall be formulated by SA in collaboration with Sector Committees or other experts or professional associations. Requirements for individual areas are provided in annexes hereto. 6 CHANGES WITH REGARD TO PREVIOUS REVISION Item 1.4 has been added regarding information on participation in ILCs. Under 2.5, guidance and reference have been added to the document on frequency of participation in ILCs (EA-4/18). An instruction has been added to 3.2 for the case of exceptions. The description under 4.1 regarding organisation/initiative of regional ILCs has been corrected. The References chapter has been updated. 7 TRANSITORY PROVISIONS N/A. 8 CONTROL OF THE DOCUMENT A valid document shall be located in i4 (SA Information System). A clean copy shall be published on the SA website, and shall be available on printed format at the SA Head Office. Printouts and copies of the document shall have informative nature and shall not be considered as controlled copies. The validity of these documents should be checked in i4 or on the SA website. 9 REFERENCES [1] SIST EN ISO/IEC 17025:2005, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:2005). [2] SIST EN ISO/IEC 17011:2004, Conformity assessment General requirements for accreditation bodies accrediting conformity assessment bodies (ISO/IEC 17011:2004). [3] EA-3/04, Use of Proficiency Testing as a Tool for Accreditation in Testing, August [4] EA-2/14, Procedure for Regional Calibration ILCs in Support of the EA MLA, European cooperation for Accreditation, June 2008, rev 00. [5] ILAC P9:11/2010 ILAC Policy for Participation in Proficiency Testing Activities [6] SIST EN ISO IEC 17043:2010 Conformity assessment General requirements for proficiency testing (ISO/CASCO 17043:2010). [7] ISO 13528:2005 Statistical methods for use in proficiency testing by interlaboratory comparisons [8] EA-4/18 TA:2010 Guidance on the level and frequency of proficiency testing participation, June 2010, rev00. Revision 4 In use as of: Page 6 of 6