The C Chart is a control chart used to track the number of defects and detect signs of special causes. To use C Chart, the subgroup size must be constant. The data is assumed to follow a Poisson distribution and the average number of defects is estimated from the data.
At the Excel Menu (For Excel 2007, go to Add-ins first)
Choose ProcessMA > Control Charts > Attributes Charts > C
In Variable, select the column containing the data (Positive integer)
In Historical Mean, enter the population mean, otherwise it will be estimated by the sample mean (Optional, Numeric)
In Control Limit Multiples, enter the position to draw the upper and lower control limits. Multiple entries must be separated by commas (Optional, Numeric, >0, Up to 3 multiples)
In Lower Limit Bound, enter the bound on the lower control limit (Optional, Numeric)
In Upper Limit Bound, enter the bound on the upper control limit (Optional, Numeric)
In Phase, select the column containing the phase indicators (Optional, >=2 distinct values)
Check the various checkboxes to perform respective tests
Click OK
You work in a paper manufacturing plant and you need to control the quality of the paper. For each batch, you inspected 100 pieces of paper to make sure that they are not stained. You want to use the C Chart to help you monitor the quality.
Open data worksheet by choosing ProcessMA > Tools > Data
Choose ProcessMA > Control Charts > Attributes Charts > C
In Variable, select S - Stained
Click OK
The process is stable as the data points are randomly distributed and lie within the control limits.
Copyright © ProcessMA