Metodologia

EAEA

Publication Reference

EA 4/02
Expression of the Uncertainty of Measurement in Calibration

PURPOSE The purpose of this document is to harmonise evaluation of uncertainty of measurement within EA, to set up, in addition to the general requirements of EAL-R1, the specific demands in reporting uncertainty of measurement on calibration certificates issued by accredited laboratories andto assist accreditation bodies with a coherent assignment of best measurement capability to calibration laboratories accredited by them. As the rules laid down in this document are in compliance with the recommendations of the Guide to the Expression of Uncertainty in Measurement, published by seven international organisations concerned with standardisation and metrology, the implementation ofEA-4/02 will also foster the global acceptance of European results of measurement.

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EA-4/02 • Expression of the Uncertainty of Measurement in Calibration

Authorship This document has been drafted by EAL Task Force for revision of WECC Doc. 191990 on behalf of the EAL Committee 2 (Calibration and Testing Activities). It comprises a thorough revision of WECCDoc. 19-1990 which it replaces. Official language The text may be translated into other languages as required. The English language version remains the definitive version. Copyright The copyright of this text is held by EA. The text may not be copied for resale. Further information For further information about this publication, contact your National member of EA. You will find the list ofmembers at the web-site: www.european-accreditation.org

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CONTENTS 1 2 3 INTRODUCTION 4 OUTLINE AND DEFINITIONS 5 EVALUATION OF UNCERTAINTY OF MEASUREMENT OF INPUT ESTIMATES 6 4 CALCULATION OF THE STANDARD UNCERTAINTY OF THE OUTPUT ESTIMATE 9 5 EXPANDED UNCERTAINTY OF MEASUREMENT 12 6STATEMENT OF UNCERTAINTY OF MEASUREMENT IN CALIBRATION CERTIFICATES 13 7 STEP-BY-STEP PROCEDURE FOR CALCULATING THE UNCERTAINTY OF MEASUREMENT 13 8 REFERENCES 14 APPENDIX A 15 APPENDIX B 18 APPENDIX C 20 APPENDIX D 21 APPENDIX E 24 SUPPLEMENT 1 27 SUPPLEMENT 2 51

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1 1.1

INTRODUCTION Thisdocument sets down the principles of and the requirements on the evaluation of the uncertainty of measurement in calibration and the statement of this uncertainty in calibration certificates. The treatment is kept on a general level to suit all fields of calibration. The method outlined may have to be supplemented by more specific advice for different fields, to make the information more readilyapplicable. In developing such supplementary guidelines the general principles stated in this document should be followed to ensure harmonisation between the different fields. The treatment in this document is in accordance with the Guide to the Expression of Uncertainty in Measurement, first published in 1993 in the name of BIPM, IEC, IFCC, ISO, IUPAC, IUPAP and OIML [ref. 1]. But whereas [ref.1] establishes general rules for evaluating and expressing uncertainty in measurement that can be followed in most fields of physical measurements, this document concentrates on the method most suitable for the measurements in calibration laboratories and describes an unambiguous and harmonised way of evaluating and stating the uncertainty of measurement. It comprises the following subjects: •definitions basic to the document; • methods for evaluating the uncertainty of measurement of input quantities; • relationship between the uncertainty of measurement of the output quantity and the uncertainty of measurement of the input quantities; • expanded uncertainty of measurement of the output quantity; • statement of the uncertainty of measurement; • a step by step procedure for calculating...