Hi,
I have data points from measurements of a certain defect. The readings are either zero(majority) or high readings.
For example: How do i get the CPK if the USL is 100? Desirable is the zero reading.
60.1 |
76.8 |
76 |
68.3 |
43.9 |
60.3 |
42.8 |
66.1 |
49.4 |
62.1 |
49.8 |
66.5 |
61.2 |
58.8 |
59.1 |
60.3 |
67.2 |
68.5 |
54.6 |
61.0 |
64.2 |
57.7 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
I suggest that you use the Distribution Platform, to help you determine the best way to calculate the Cp/Cpk. If you startup the Distribution Platform, and then under the red triangle, go to:
Continuous Fit==>All
it will help you determine which distribution best fits your data, and then under that distribution, it will give you the Cp/Cpk.
jabenir, There is one fundamental question you have to answer before calculating Capability Indices: Is your process in statistical control? If the process is not in a "reasonable degree of control", then Capability Analysis is meaningless. As Dr. Wheeler says in one of his books: "What can be said for the capability of a process not I statistical control? Not much!"
Other questions that need to be answered BEFORE a Capability Analysis: Is the data you presented in time order? If not, what is the order and what does a Runs Chart and/or Process Behavior Chart look like? Can you determine defect rates for discrete periods of time with rational sub-grouping?