User's Manual Part 3

♦367♦ MEGAM.O.L.E.® Help System Guide
indicates how well the process would be able to stay within the specified limits if the
data were perfectly centered between those limits.
Cpk compares the widest half of the data distribution to the appropriate specification
limit. It indicates whether the process is capable of meeting the specification as
indicated by the “worst half” of the measurements. Unlike Cp, the Cpk index measures
process capability without assuming the data is well-centered.