Defects per million opportunities explained
In process improvement efforts, defects per million opportunities or DPMO (or nonconformities per million opportunities (NPMO)) is a measure of process performance. It is defined as
A defect can be defined as a nonconformance of a quality characteristic (e.g. strength, width, response time) to its specification. DPMO is stated in opportunities per million units for convenience: Processes that are considered highly capable (e.g., processes of Six Sigma quality) are those that experience fewer than 3.4 defects per million opportunities (or services provided).
Note that DPMO differs from reporting defective parts per million (PPM) in that it comprehends the possibility that a unit under inspection may be found to have multiple defects of the same type or may have multiple types of defects. Identifying specific opportunities for defects (and therefore how to count and categorize defects) is an art, but generally organizations consider the following when defining the number of opportunities per unit:
- Knowledge of the process under study
- Industry standards
- When studying multiple types of defects, knowledge of the relative importance of each defect type in determining customer satisfaction
- The time, effort, and cost to count and categorize defects in process output
Other measures
Other measures of process performance include:
Further reading
- Book: Adams . Cary W. . Gupta . Praveen . Charles E. . Wilson . Six Sigma Deployment . Butterworth-Heinemann . 2003 . Burlington, MA . 0-7506-7523-3 . 50693105 .
- Book: Breyfogle, Forrest W. III . Forrest Breyfogle . Implementing Six Sigma: Smarter Solutions Using Statistical Methods . John Wiley & Sons . 1999 . New York, NY . 0-471-26572-1 . 50606471 .
- Book: De Feo . Joseph A. . Barnard . William . JURAN Institute's Six Sigma Breakthrough and Beyond – Quality Performance Breakthrough Methods . McGraw-Hill Professional . 2005 . New York, NY . 0-07-142227-7 . 52937531 .
- Hahn, G. J., Hill, W. J., Hoerl, R. W. and Zinkgraf, S. A. (1999) The Impact of Six Sigma Improvement-A Glimpse into the Future of Statistics, The American Statistician, Vol. 53, No. 3, pp. 208–215.
- Book: Keller, Paul A. . Six Sigma Deployment: A Guide for Implementing Six Sigma in Your Organization . Quality Publishing . 2001 . Tucson, AZ . 0-930011-84-8 . 47942384 .
- Book: Pande . Peter S. . Neuman . Robert P. . Roland R. . Cavanagh . The Six Sigma Way: How GE, Motorola, and Other Top Companies are Honing Their Performance . McGraw-Hill Professional . 2001 . New York, NY . registration . Pande Six Sigma Way. . 0-07-135806-4 . 647006794 .
- Book: Pyzdek, Thomas . Paul A. Keller . amp . The Six Sigma Handbook, Third Edition . McGraw-Hill . 2009 . New York, NY . 978-0-07-162338-4 . 51194565 .
- Book: Snee . Ronald D. . Hoerl . Roger W. . Leading Six Sigma: A Step-by-Step Guide Based on Experience with GE and Other Six Sigma Companies . FT Press . 2002 . Upper Saddle River, NJ . 0-13-008457-3 . 51048423 .
- Book: Taylor, Gerald . Lean Six Sigma Service Excellence: A Guide to Green Belt Certification and Bottom Line Improvement . J. Ross Publishing . 2008 . New York, NY . 978-1-60427-006-8 . 271773742 .
- Book: Tennant, Geoff . SIX SIGMA: SPC and TQM in Manufacturing and Services . Gower Publishing, Ltd . 2001 . Aldershot, UK . 0-566-08374-4 . 44391556 .
Notes and References
- Book: http://www.itl.nist.gov/div898/handbook/pmc/section1/pmc16.htm. What is Process Capability? . 2008-06-22 . NIST/Sematech Engineering Statistics Handbook . National Institute of Standards and Technology.