Bob Luttman, Robert Luttman & Associates
Control Charts - Summary
The control chart equations are a bit intimidating, however all statistical software and nearly all spreadsheets can generate control charts. We have developed control chart applications using database, statistical, and spreadsheet software. Contact us to build and application for you.
We have presented the basics of control charts and introduced you to the most frequently use charts. Control charts are a powerful, simple, and graphical tool for managing processes. They are an especially useful tool for dynamic processes such as most clinical processes.
To summarize the control chart material:
- Types of Variation
- Common Cause - Normal random process noise.
- Special Cause - Significant signal of a significant with an assignable cause.
- Types of Data
- Attributes - Characteristic or categorized data rather than the data itself.
- Variables - Numeric data.
- Variables data is convertible to attribute data but important information is lost.
- Finding Special Cause Variation
- Control Limit tests
1 point outside three standard deviation limits.
2 of 3 consecutive points outside two standard deviation limits.
4 of 5 consecutive points outside one standard deviation limits.
- Other tests
Run of six or more points up or down.
Run of six or more points above or below median.
Run of 14 or more consecutive points in up/down sawtooth pattern.
- Control Limit tests
- Control Chart Types
- Variables
- Individuals
X-bar/R
X-bar/S
- Individuals
- Attributes
- p chart
np chart
c chart
u chart
- p chart
- Variables
