Statistical process control aims to reduce variation in products and services by distinguishing between common cause variation, which is normal variation, and special cause variation, which occurs when something changes in the process. It does this by using statistical limits and control charts to detect when a process shifts due to special causes of variation. Histograms can also be used to visualize reductions in variation by comparing data from before and after quality improvement efforts.

1. Statistical Process Control
in a Nutshell
Reality: Every Process Varies
Goal: Reduce Variation in Products and Services
Types of Variation
•Special Cause Variation
(something changed)
•Common Cause Variation
(normal variation)

2. SPC in a Nutshell
It’s possible to calculate statistical limits
for any type of data and any pattern of variation.
Using these “control” limits, it’s possible to create rules to
detect special causes of variation whenever a process shifts.

3. Statistics or Charts?
• Normality?
• Means?
• Variances?

4. Reducing Variation
Before After

5. Reducing Variation
Use Histograms to show reduction in variation
Before After

6. http://www.visual-literacy.org/periodic_table/periodic_table.html

7. Periodic Table of Visual Methods
http://www.visual-literacy.org/periodic_table/periodic_table.html

8. QI Macros SPC Software for Excel
www.qimacros.com
Data Analysis & Projects
Lean Six Sigma Demystified
www.lssyb.com