Abstract

Millions of measuring instruments are verified each year before being placed on the markets worldwide. In the EU, such initial conformity assessments are regulated by the Measuring Instruments Directive (MID). The MID modules F and F1 on product verification allow for statistical acceptance sampling, whereby only random subsets of instruments need to be inspected. This article re-interprets the acceptance sampling conditions formulated by the MID. The new interpretation is contrasted with the one advanced in WELMEC guide 8.10, and three advantages have become apparent. First, an economic advantage of the new interpretation is a producers’ risk bounded from above, such that measuring instruments with sufficient quality are accepted with a guaranteed probability of no less than 95%. Second, a conceptual advantage is that the new MID interpretation fits into the well known, formal framework of statistical hypothesis testing. Thirdly, the new interpretation applies unambiguously to finite-sized lots, even very small ones. We conclude that the new interpretation is to be preferred and suggest re-formulating the statistical sampling conditions in the MID. Re-interpreting the MID conditions implies that currently available sampling plans are either not admissible or not optimal. We derive a new acceptance sampling scheme and recommend its application. Supplementary materials for this article are available online.

摘要

每年有数以百万计的测量仪器在投放全球市场之前经过验证。在欧盟，此类初始合格评定受测量仪器指令 (MID) 监管。产品验证中的 MID 模块 F 和 F1 允许统计验收抽样，从而只需要检查仪器的随机子集。本文重新解读了MID制定的验收抽样条件。新的解释与 WELMEC 指南 8.10 中先进的解释相比，三个优势变得明显。首先，新解释的经济优势是生产者的风险自上而下，因此质量足够的测量仪器被接受的概率不低于 95%。第二，一个概念上的优势是新的 MID 解释符合众所周知的统计假设检验的正式框架。第三，新解释明确适用于有限大小的地块，即使是非常小的地块。我们得出的结论是新的解释是首选的，并建议重新制定 MID 中的统计抽样条件。重新解释 MID 条件意味着当前可用的抽样计划要么不可接受，要么不是最佳的。我们推导出一个新的验收抽样方案并推荐其应用。本文的补充材料可在线获取。我们得出的结论是新的解释是首选的，并建议重新制定 MID 中的统计抽样条件。重新解释 MID 条件意味着当前可用的抽样计划要么不可接受，要么不是最佳的。我们推导出一个新的验收抽样方案并推荐其应用。本文的补充材料可在线获取。我们得出的结论是新的解释是首选的，并建议重新制定 MID 中的统计抽样条件。重新解释 MID 条件意味着当前可用的抽样计划要么不可接受，要么不是最佳的。我们推导出一个新的验收抽样方案并推荐其应用。本文的补充材料可在线获取。