Publication Sponsored by the Society's Fastness Tests Co–ordinating Committee –XLVI

Abstract

Nottingham NG7 6LD Statistical data from an interlaboratory trial of a new test method are applied to yield advice on qualitycontrol criteria. It is shown how repeatabilities and reproducibilities of the test can be converted into critical differences for comparison with a specified fastness rating. Adding the right critical difference to the rating tells one what result to lay down as a qualitycontrol target for a defined, high probability of the bulk goods conforming to the specified rating. The difference between 'two-tailed'and 'one-tailed'limits is explained. The stages in the procedure described inclu der correlating critical difference with fastness rating; comparing limits for different numbers and types of tests and assessors; suggesting the most useful procedures; deriving the minimum results needed to satisfy different specifications for the particular test; and explaining the related appendix to the test method on precision for quality control. Information is given on ways to alter limits according to particular nmds.