Glossary Item






Statistical Process Control

 

SPC is a set of business practices that uses statistical techniques to control processes based upon sample measurements. Conceptually, SPC assumes that the variance in any process will tend to approximate the traditional bell curve - where 95% of the observations are within 2 standard deviations (sigma) from the mean, and 99.7% are within 3 standard deviations. If the sample observations fall within these limits, then the process is considered to be in control. If the observations is outside of these limits, then there is something wrong and investigation and/or adjustment is indicated.

With the advent of the computer, SPC has become far more complicated in terms of features and math, and can handle many different scenarios, but the basic concept of using statistical methods to manage the process rather than 100% inspection continues.

SPC is applicable to any process that has measurable outcomes not just manufacturing, and can often prove to be superior to 100% inspection as it allows the operator to see trends and process shifts over time that are obscured in 100% of the data - it allows the operator to see the forest, not just the trees.

WEBSITES:
      * http://en.wikipedia.org/wiki/Normal_distribution

      * http://www.ms.uky.edu/~mai/java/stat/GaltonMachine.html

      * http://en.wikipedia.org/wiki/Statistical_process_control

      * http://www.isixsigma.com/st/control_charts/



Learn more...

To discuss your needs, contact us at info@qic-intl.com

This page last updated: 02/20/2012