• occurs prior to implementation
• preferred
Prospective
• occurs during actual use of process
• simultaneous
Concurrent
• occurs after production use has occurred
• based on review of historic info
Retrospective
• Non-conformance to a standard or requirement
• Undesired characteristic of a raw material or product which indicates that it failed
to conform to the standard
Defects
all test results that fall outside the
specifications
Out-of-specification (OOS)