Statistical Process Control

Statistical Process Control (SPC) is a structured approach for monitoring and controlling a process using statistical techniques applied to data collected over time.

In manufacturing and other operations, SPC typically involves:

• Defining key product or process characteristics to measure (such as dimensions, weight, or cycle time).
• Collecting data from the process at regular intervals or by sampling.
• Plotting the data on control charts that distinguish routine variation from unusual variation.
• Interpreting chart patterns and signals to determine whether the process is statistically stable or changing.
• Investigating and addressing identified special causes of variation through problem-solving methods, such as Root Cause Analysis.
• Documenting limits, rules, and responses so that process operators and engineers handle signals consistently.

SPC does not by itself specify what changes to make to a process; it provides a way to detect and characterize variation so that teams can decide when and where to apply corrective or preventive actions.