A free online reference for statistical process control, process capability analysis, measurement systems analysis, control chart interpretation, and other quality metrics.
What are the measures of process capability?
These indices show what the process is “capable” of doing. This is the six sigma range of the inherent variation of a statistically stable process. Sigma is estimated using the /d2 formula.
What are the measures of process performance?
These indices show what a process is actually doing. This is the six sigma range of the total process variation, where sigma is usually determined by the sample standard deviation.
All of these capability indices can be calculated using software packages like SQCpack.
See also: >> Can a process produce output within specifications? >> Control vs capability >> Normal data capability analysis >> Non-normal data capability analysis >> What is capability analysis and when is it used? >> Learning more about capability