For my Attribute Charts we add Cpk and Cp to the Chart Data. They render fine when we do Auto Calculate. My users wanted to know how those values are calculated for Attribute Charts. I looked through the document "QCSPCChart SPC Control Chart Tools for .Net" 12/23/2013 Rev. 2.3 and I only found the formula for Variable Control Charts. Thanks in advance. Please let me know if you need more information.
The Process Performance (Ppk...) and Process Capability (Cpk...) indices in the software are only applicable to Variable control charts. They have no meaning in attribute control charts.The theory behind Process Performance and Process Capability indices depends on measured variables which are continuous in nature, and not the binary (pass/fail) nature of the measured variables in attribute control charts. So even though the software will calculate these values, it has no meaning in attribute control charts.
Formula for Process Cap Cpk in Attribute Chart(s)
Posted - 15 Jul 2014 : 18:59:45
