Why misuse the term ‘defects’?

Stating that 6 Sigma performance represents 3.4 defects per million opportunities may not always be the best use of the term ‘defects’.

In some instances it should be replaced by ‘non-conformities’. However, in Six Sigma improvement projects one is not always confined to dealing with non-conformities as such. Sometimes the term ‘non-conforming items’, ‘events’ or ‘values’ is more appropriate. Organizations are advised to take heed of ISO 9000:2000 Quality management systems – Fundamentals and vocabulary. ISO 9000 states that the term ‘defect’ should be used with extreme caution.

It warns us that the distinction between defect and non-conformity is important because of its legal connotations, particularly those associated with product liability issues. To minimize risk it is strongly I recommended that in the phrase ‘defects per million opportunities’ defects be replaced by ‘non-conformities (or more generally, events) per million opportunities’ in Six Sigma applications.