c-chart: When is it used?

A c-chart is particularly useful when the item is too complex to be ruled as simply conforming or nonconforming. For example, an automobile could have hundreds of possible defects yet still not be considered defective. A c-chart could also be used to monitor the number of phone calls received in a given period of time such as an hour or a day.

Use c-charts when you can answer yes to these questions:

1. Do you need to assess system stability?

2. Is the data the number of nonconformities per subgroup?

3. Are the subgroups the same size?

4. Have the possible nonconformities been identified prior to data collection?

5. Is the time order of subgroups preserved?

See also:
>c-chart: What is it?
>c-chart: What does it look like?
>c-chart: Getting the most