A statistical measure assesses the consistency of a process relative to its specification limits. It quantifies the ability of a process to produce output within predefined boundaries. For example, a manufacturing process aims to produce parts with a target diameter of 10mm, and acceptable limits of 9.9mm and 10.1mm. This analysis would determine if the process consistently yields parts within this range.
The assessment of this consistency offers several advantages. It allows organizations to understand process performance, identify areas for improvement, and predict future output quality. Historical context reveals its evolution alongside quality management principles, emphasizing data-driven decision-making for process optimization and reduced variability.