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Apps / Capability

Process Capability Analyzer

Analyze capability using raw data points or summary statistics. This app calculates Cp, Cpk, Pp, Ppk, estimated ppm defective, a histogram with normal curve overlay, a normality screening flag, and a control-chart preview with what-if adjustments for centering and tolerance changes.

Analyzer

Choose an input method

Capability core: Cp = tolerance width / (6 x within sigma), Ppk = min(Ppu, Ppl)

Input mode

Paste values separated by commas, spaces, or line breaks. CSV uploads can contain a single numeric column or mixed text; the app extracts numeric values automatically.

Mean shift: 0.00

Tolerance factor: 1.00x

Raw-data mode estimates overall sigma from the full data set and within sigma from average moving range. Summary mode uses the entered overall sigma and defaults within sigma to that same value unless you provide a separate within estimate.

Histogram

Capability histogram with normal overlay

Control Chart

I-chart preview

Instructions

How to use this app

  1. Select Raw data points if you have individual measurements, or Summary statistics if you only have mean and sigma values.
  2. Enter or upload the data, then provide LSL, USL, and a target value.
  3. Click Analyze to calculate Cp, Cpk, Pp, Ppk, Cpu, Cpl, and estimated ppm defective.
  4. Use the centering and tolerance sliders to explore how process mean shifts or tolerance tightening affect capability.
  5. Use Export Control Chart to download the current control-chart preview as a PNG image.

Cp and Cpk use within sigma, which is meant to reflect short-term process spread. Pp and Ppk use overall sigma, which reflects long-term observed spread. If Ppk trails Cpk significantly, the process may be drifting over time even if short-term performance looks acceptable.

The normality flag is a screening aid based on skewness and kurtosis. It is useful for quick review, but it is not a substitute for a full normality study when the decision is high stakes.