Process Capability Six-Pack: See Full Process Capability in One Report
What is the Capability Six-Pack?
The six-pack combines a histogram with a normal fit curve, a capability index table (Cp/CpK/Pp/PpK), an Xbar-R or I-MR control chart and a normal probability plot into one process capability report, following the Minitab layout. It answers three questions at a glance: is the data normal, is the process in control, and is the capability adequate. The layout is an industry de facto standard that customers and management read immediately.
When to Use It
Use the six-pack for PPAP/APQP capability submissions, for capability reviews with customers or management, and for a fast diagnosis of normality, control and capability in one pass. It replaces several disconnected charts with one standardized summary, cutting review time and eliminating inconsistent calculation bases. Regenerate the report whenever data are updated so the whole set stays current.
How to Use It (Step by Step)
Paste the data and the tool automatically selects Xbar-R or I-MR control charts based on subgroup structure, then builds the full report. Read it in order: the normal probability plot confirms the distribution assumption, the control chart confirms stability, the histogram shows shape relative to the specification, and the index table gives the capability grade. If any step fails, return to the data and resolve it before interpreting capability.
Key Formulas / Example
The report combines the standard capability indices Cp, CpK, Pp and PpK with control chart limits computed from the data. Within-subgroup sigma is estimated from the average subgroup range (Rbar/d2) and reflects short-term variation, while overall sigma is the standard deviation of all data and reflects long-term variation. A large gap between the two indicates batch-to-batch drift, which is exactly the difference between Cp and Pp.