Statistical Process Control to Monitor Process

12:11 AM Posted by IQMS Global

Very often we come across the term SPC or Statistical Process Control in manufacturing organizations.Statistical Process Control (SPC) involves using statistical techniques to measure and analyze the variation in processes. Most often used for manufacturing processes, the intent of SPC is to monitor product quality and maintain processes to fixed targets. Statistical quality control refers to using statistical techniques for measuring and improving the quality of processes and includes Statistical Process Control in addition to other techniques, such as sampling plans, experimental design, variation reduction, process capability analysis, and process improvement plans.

Statistical Process Control is used to monitor the consistency of processes used to manufacture a product as designed. It aims to get and keep processes under control. No matter how good or bad the design, SPC can ensure that the product is being manufactured as designed and intended. Thus, Statistical Process Control will not improve a poorly designed product's reliability, but can be used to maintain the consistency of how the product is made and, therefore, of the manufactured product itself and its as-designed reliability.

Statistical Process Control was pioneered by Walter A. Shewhart in the early 1920s. W. Edwards Deming later applied SPC methods in the United States during World War II, thereby successfully improving quality in the manufacture of munitions and other strategically important products. Deming was also instrumental in introducing SPC methods to Japanese industry after the war had ended.


The followings are the major benefits of SPC for an organization:

  • Provides surveillance and feedback for keeping processes in control
  • Signals when a problem with the process has occurred
  • Detects assignable causes of variation
  • Accomplishes process characterization
  • Reduces need for inspection
  • Monitors process quality
  • Provides mechanism to make process changes and track effects of those changes
  • Once a process is stable (assignable causes of variation have been eliminated), provides process capability analysis with comparison to the product tolerance

Statistical Process Control is used everywhere, behind the scenes. It is a verifiable way to better understand and make sense of variation. Statistical Process Control (SPC) is an optimization philosophy centered on using a variety of statistical tools to enable continuous process improvement. Closely linked to the total quality management (TQM) philosophy, SPC helps firms to improve profitability by improving process and product quality. Although initially used in manufacturing, Statistical Process Control tools and methods work equally well in a service environment.

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