Quality
Pp / Ppk
Process Performance Index · pp · ppk · process performance
TL;DR
Long-term process-performance indices — same formula as Cp/Cpk but using overall (long-term) sigma. The honest number for ongoing capability.
Pp and Ppk use overall (long-term) sigma — including between-batch variation, operator drift and shift-to-shift effects. Pp/Ppk are almost always lower than Cp/Cpk. Inspectors looking at your CPV report want Ppk, not Cpk; Cpk hides real-world variation.
V5 separates within-batch (Cp/Cpk) and overall (Pp/Ppk) calculations so quality teams can spot whether variation is process-inherent or drift over time.
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