Lot Acceptance Procedure Criteria-Providing Statistical Confidence to Pass

摘要

Q. Lots are released based on comparing test results from a sample to lot acceptance procedure criteria. If a set of test results meets the lot acceptance procedure criterion, how can I be assured that another sample from the lot would also pass the criterion? A: Companies use lot acceptance procedures to release a lot. Test results from a sample are evaluated against lot acceptance procedure criteria, and if the criteria are met, the lot is released. However, since test results are subject to variability, another sample from the same lot may not meet the criteria. If units from a lot fail after release, there can be significant cost to the company (e.g., a lot recall). ASTM E2709, Practice for Demonstrating Capability to Comply with an Acceptance Procedure, provides a general statistical approach that can be used to make a statement such as this one: "With 95 percent confidence, there is a 95 percent chance that another sample taken from the lot will pass the lot acceptance procedure."