Hi All, I working on Process capability study for my project. I have a question on entering the data points. I have taken 25 Months data, wherein 12 Months are zero defects and other months have Defects less than 3. Do I need to include all 25 Months of data or only the 13 months data which has defect numbers. Can someone explain how to calculate the Cp and Cpk for these type of processes.