21 CFR 820 - 820.250 statistical techniques
Original text
Expert opinion
(a) Where appropriate, each manufacturer shall establish and maintain procedures for identifying valid statistical techniques required for establishing, controlling, and verifying the acceptability of process capability and product characteristics.
(b) Sampling plans, when used, shall be written and based on a valid statistical rationale. Each manufacturer shall establish and maintain procedures to ensure that sampling methods are adequate for their intended use and to ensure that when changes occur the sampling plans are reviewed. These activities shall be documented.
Statistical techniques need to be implemented where certainty of meeting specifications, process capability or reliability is important.
In the case that sampling plans are used, for example when approaching the matter via a DoE (design of experiments), these have to be made available in writing. The sampling plans should be based on a procedure and statistical rationale. The procedure must reflect the nature of statistical problem and sampling and maintained also when changes occur.
