BS PD CEN/TR 16797-2:2015

BS PD CEN/TR 16797-2:2015 provides guidance on the statistical assessment of declared values with respectto the release, emission and/or content of dangerous substances. This report provides statisticallybasedcriteria for type-testing (TT), further-testing (FT) and where a product has been shown to beconsistent with measured values for the release, emission or content that are significantly below thedeclared values, the point where no-further-testing (NFT) is permitted.A series of fundamental principles are defined in CEN/TR 16797-1 and two statistical approaches aredefined. The first approach is to use assessment by variables and this approach requires the data tobe normally or log-normally distributed. This approach is recommended as the default option. Thealternative approach based on assessment by attributes is appropriate for data sets that are notnormally or log-normally distributed. The downside to this form of assessment is that more test dataare needed for the same level of reliability. CEN/TR 16797-1 introduces these assessment proceduresand CEN/TR 16797-2 provides more detail and the statistical proof that they satisfy the principlesdefined in CEN/TR 16797-1. With both of these approaches the minimum frequency of testing is afunction of the distance between the mean value and declared value and the variability of the data set,i.e. the sample standard deviation.To reduce the costs of testing, production plants producing a similar product may share data, e.g. begrouping the product into clusters for statistical assessment of declared values. Rules for the use ofclusters are given in this document.This document also contains rules for identifying outliers within a data set and guidance on using testsother than the reference method for FT.A list of tasks for product technical committees is given in this document as is a model clause forincluding in product standards and rules of applications that may be cited in the product standard orcopied into product standards.Cross References:CEN/TR 16797-1:2015CEN/TR 15858CEN/TR 16220DS 129rev5:2010CEN/TC 351 N 0286CEN/TR 16496:2013EN 16687ISO 3534-1ISO 3534-2ISO 5725-1ISO 5725-2