Advanced capability
Separates overall from within variation and supports either a raw-scale normal model or a Box–Cox transformation for positive data, with specification limits transformed consistently.
Your data
One measurement per row in time order. Enter LSL/USL and declare subgroup size only when consecutive measurements truly form rational subgroups.
CSV/TXT without a header or pasted from Excel. Separator: semicolon or TAB; decimal separator: dot or comma. Maximum 200 observations in total, not 200 per group. Data is processed in the browser and is not uploaded to the server.
About the calculation
Pp/Ppk use overall variation. Cp/Cpk use within-subgroup variation estimated from declared rational subgroups. In Box–Cox mode, QAPP selects λ by probability-plot correlation and applies the same monotonic transform to the data, LSL and USL.
Calculations run locally in the browser. Statistical distributions and functions use jStat 1.9.6; values are rounded only for display. For method selection, conditions of use and interpretation criteria, see the “Sources and methodological alignment” section above and any customer-specific requirements.
Ready for your data
Upload a dataset or use the example, then click “Calculate results”. Results will include charts, values and interpretation conditions.