Cpk=Process Capability Index. This adjusts the Cp for the effect of noncentered distribution.
Ppk=Process Performance Index. This adjusts the Pp for the effect of noncentered distribution.7
In looking at a graphic representation Fig. 10.47 shows the results of different levels of Cp. Note that with a Cp of less than 1 the production is very spread out within the set limits. While a Cp value >1 shows a very tight fit of all data points. Another way of looking at it and interpreting the results of the calculations is: