SPC: Statistical Process Control

In this issue: Introduction to Statistical Process Control

A process is under statistical control when the process is stable and capable.

A process is said to be stable when it is only influenced by common causes of variation. These are variations that are inherent to the process.

If there are variations not inherent to the process (special causes of variation), they must be identified and removed before proceeding any further.

A process is capable when the parameters we measure meet the engineering specifications and requirements.

Statistical Process Control (SPC) is a method of monitoring a process during its operation.

The goal of SPC is to

control the quality of the products while they are produced
monitor the performance of the process
determine quickly when a process is out of control
determine how much variation in the process is due to common cause variation, and how much is due to special cause variation

Next week we discuss Statistical Process Control Methods