Module capability 

Process capability analysis.

Computes standard capability indices for assessing how well a process meets specification limits.

Indices

• Cp — Potential capability (spread vs tolerance)
• Cpk — Actual capability (centering considered)
• Pp, Ppk — Long-term performance indices
• Cpm — Taguchi capability (target deviation)

Sigma Level

• sigma_to_ppm — Convert sigma level to PPM defect rate
• ppm_to_sigma — Convert PPM defect rate to sigma level

References

• Montgomery (2019), Introduction to Statistical Quality Control, 8th ed.

Structs

CapabilityIndices

Computed capability indices.

ProcessCapability

Input specification for process capability analysis.

Functions

ppm_to_sigma

Converts a parts-per-million (PPM) defect rate to a sigma quality level.

sigma_to_ppm

Converts a sigma quality level to parts-per-million (PPM) defect rate.