What is a Control Chart?
Control Charts Evaluate Process Performance Over Time
Control charts were developed in the 1920's by Dr Walter Shewhart while working at Western Electric Company. Shewhart introduced the control chart as a way to monitor a process and distinguish between:
- Assignable or Special Cause Variation - needs to be investigated
- Chance or Common Cause Variation - normal, does not require any action.
Control Charts Contain These Key Elements
An Upper Control Limit (UCL) line calculated at 3 sigma above the Center Line.
A line chart of data measuring the process over time.
A Center Line calculated as the average or median of the data.
A Lower Control Limit (LCL) line calculated at 3 sigma below the Center Line.
Think of a control chart as a line graph with built in intelligence that helps you determine what it is telling you.
Three Reasons You Need Software to Create a Control Chart
There are seven Shewhart control charts and many more for special situations.
Each type of control chart has a different formula for calculating control limits.
Stability rules identify and highlight points or trends that need to be investigated. They vary by industry.
Here is a Control Chart Created Using QI Macros Add-in for Excel
I purchased the QI Macros just to run control charts (worth the price just for that). I had NO idea what a robust product you have developed, and what an amazing bargain I was getting. File me under exceeded customer expectations.
- Scott Campbell
Why Choose QI Macros Over Other Control Chart Software?
- Only $249 - less with quantity discounts
- No annual fees
- Free Technical Support
Easy to Use
- Works Right in Excel
- Create a Chart in Seconds
- Easy to Customize & Share Charts
Proven and Trusted
- 100,000 Users in 80 Countries
- Celebrating 20th Anniversary
- Five Star CNET Rating - Virus Free
QI Macros Unique Features
Once you create a control chart, its easy to update or customize it using the Control Chart Tools Menu.
- Show process changes
- Add target or goal lines
- Update and change control limit calculations
- Update stability analysis
- Customize charts
- Variable, Attribute and Other Types of Control charts available in QI Macros
- Watch Control Chart Video
- Control Chart Quick Reference Card (PDF, 238 KB)