不确定度的表示方式应用指南.doc

校准和测量能力(CMC)的表示方式应用指南 中国合格评定国家认可委员会（CNAS）于2011年2月15日发布了CNAS-CL07:2011《测量不确定度的要求》，并于2011年5月1日正式实施，该文件中关于校准实验室测量不确定度的要求等同采用了国际实验室认可合作组织（ILAC）ILAC-P14:2010《校准领域测量不确定度的政策》（2011年11月1日实施）的内容。目前CNAS认可的部分校准实验室“校准和测量能力”（以下简称CMC）的表示方式不能满足上述文件的要求，因此CNAS秘书处于2011年9月23日发文（认可委（秘）（2011）118号）要求校准实验室对CMC的表示方式进行核查和修改。 为了更好地完成此次CMC核查工作，CNAS秘书处组织编制了本文件，供校准实验室和校准领域评审员参考。在使用时应注意，本指南中的CMC示例仅作为CMC表示方式的示范，实验室应根据实际评估结果确定表示方式和数值。 一、文件要求 ILAC-P14:11/2010《校准领域测量不确定度的政策》[注1]相关条款： 5.2 There shall be no ambiguity on the expression of the CMC on the scopes of accreditation and, consequently, on the smallest uncertainty of measurement that can be expected to be achieved by a laboratory during a calibration or a measurement. Particular care should be taken when the measurand covers a range of values. This isgenerally achieved through employing one or more of the following methods for expression of the uncertainty: a) A single value, which is valid throughout the measurement range. b) A range. In this case a calibration laboratory should have proper assumption for the interpolation to find the uncertainty at intermediate values. c) An explicit function of the measurand or a parameter. d) A matrix where the values of the uncertainty depend on the values of the measurand and additional parameters. e) A graphical form, providing there is sufficient resolution on each axis to obtain at least two significant figures for the uncertainty. Open intervals (e.g., “U x”) are not allowed in the specification of uncertainties. 5.3 The uncertainty covered by the CMC shall be expressed as the expanded uncertainty having a specific coverage probability of approximately 95 %. The unit of the uncertainty shall always be the same as that of the measurand or in a term relative to the measurand, e.g., percent. Usually the inclusion of the relevant unit gives the necessary explanation. 注1：ILAC-P14:11/2010全文可从以下地址下载： /documents/ILAC_P14_12_2010.pdf CNAS-CL07:2011《测量不确定度的要求》第7.1条等同转化了ILAC-P14的如上内容： 7. 对校准和测量能力（CMC）的要