What Do the Process Capability/Performance Metrics Measure?

Quick Links

SPC for Excel Software

Visit our home page

SPC Training

SPC Consulting

Ordering Information

Thanks so much for reading our publication. We hope you find it informative and useful. Happy charting and may the data always support your position.


Dr. Bill McNeese
BPI Consulting, LLC

View Bill McNeese

Connect with Us

Comments (7)

  • Newton GreenDecember 31, 2020 Reply

    Best article about process capability I've ever read; thank you Bill!  Despite using process capability metrics for several years, I finally understand why Cp and Cpk use sigma (as calculated from the average range) for variation, and why Pp and Ppk use s, the historical standard deviation.  After reading this article, the light came on.  I feel chagrined that I didn't get this before.  The numerical examples provided terrific clarification to send this point home.Thank you again for posting these articles each month, which have been enormously helpful.  I always make sure I read each one.

    • billDecember 31, 2020 Reply

      Thank you very much for the kind comments!

  • SharleneJune 22, 2021 Reply

    Fantastic paper. Thank you for simplifying the learning process. I finally understand SPC 100%

  • Akash JaiswalAugust 25, 2021 Reply

    Best explaination of all the four metrices in the most simplest way, I've ever come across. Thank You very much. 

  • CanIndian ChannelFebruary 8, 2022 Reply

    How does a quality engineer or a cad designer decide which dimension to CpK, is there a criteria? 

    • billFebruary 8, 2022 Reply

      I would  say it is usually the dimensions critical to the customer.

  • Bester ChikafutwaOctober 12, 2022 Reply

    I have read many books on process capability because i couldnt really connect many of the bits and pieces i was getting from the other materials. This article has enlightened and helped me understand the fundamental principle for the concepts. Especially how to determine the short term and the long term and apply relevant calculations. This will be of great help in my Lean Six Sigma course. Thank you!

Leave a Reply

Your email address will not be published. Required fields are marked *