Computing CPK for bimodal data, either large readings or zero (majority)..<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />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 |
Re: Computing CPK for bimodal data, either large readings or zero (majority)..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?
Re: Computing CPK for bimodal data, either large readings or zero (majority)..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.
