Statistical Process Control

What is Statistical Process Control?

A method to apply statistics to identify and fix quality control problems, developed by Dr. Walter A. Shewhart in the 1920s.

How are Common Causes of variation addressed?

By fixing or changing the system, often requiring management involvement (e.g., changing materials or process design).

The design of a product is causing quality control issues. This is an example of a which type of cause?

Common

What are the two causes of variation in Statistical Process Control?

Common Causes (from stable systems, part of the normal process) and Special Causes (from specific issues or events, not typical).

Implementing a change in the process is part of which step of PDSA?

Do

How does the Act step relate to the Planning step of PDSA?

The process is cyclic so Act leads to Planning

How are Special Causes of variation addressed?

Can often be changed quickly and easily without management intervention (e.g., fixing a malfunctioning machine).

How do Common and Special Causes differ in their occurrence and distribution?

Common causes are usually normally distributed. Special causes lie outside the normal distribution and are not routine.

What is the PDSA cycle in Statistical Process Control?

Plan (identify problem and cause), Do (implement a change), Study (analyze data), Act (standardize or modify the change). A continuous improvement cycle.

A cause of variation that comes from a specific event or issue is what type of cause?

Special

After figuring out whether a change reduces variation, the PDSA method requires that the company do which of the following?

Act

How can Statistical Process Control be applied in a real-world scenario?

Mario's shoe factory uses it to identify whether shoe defects are due to common causes (e.g., substandard materials) or special causes (e.g., machine malfunction).