c Chart in Excel
Use a c chart for "counted" data when the opportunity is large compared to the actual number of defects.
The c chart is used to evaluate process stability when counting defects or errors and when the sample size is constant. For example injuries per month or falls per month.
Example of a c chart created by QI Macros for Excel.
c chart data consists of one column of integers:
To create a c chart in Excel using QI Macros:
- Just click and drag over the data to select it.
- Then click on the QI Macros menu, Control Charts, then c chart.
- QI Macros will all of the math and draw the c chart for you. QI Macros will also turn any unstable points or conditions on the c chart red. These should be investigated.
- Control Chart Quick Reference Card (PDF, 238 KB)