Design Control Guidance - Food and Drug Administration

Another self-documenting verification method is the traceability matrix. This method isparticularly useful when the design input and output are both documents; it also has greatutility in software development. In the most common form of the traceability matrix, theinput requirements are enumerated in a table, and references are provided to each sectionin the output documents (or software modules) which address or satisfy each inputrequirement. The matrix can also be constructed “backwards,” listing each feature in thedesign output and tracing which input requirement bears on that feature. This reverseapproach is especially useful for detecting hidden assumptions. Hidden assumptions aredangerous because they often lead to overdesign, adding unnecessary cost and complexityto the design. In other cases, hidden assumptions turn out to be undocumented designinput requirements which, once exposed, can be properly tracked and verified.However, many verification activities are simply some sort of structured assessment of thedesign output relative to the design input. When this is the case, manufacturers maydocument completion of verification activities by linking these activities with the signoffprocedures for documents. This may be accomplished by establishing a procedurewhereby each design output document must be verified and signed by designated persons.The presence of the reviewers’ signatures on the document signifies that the design outputhas been verified in accordance with the signoff procedure.Section F. Design Verification 3/11/97 Page 32