Cpm is a capability index, also known as the Taguchi capability index, that is a function of the specification limits, mean of the process, and a provided target, T.

The indices of Cpk and Ppk focus on centering of the mean of the distribution around the midpoint of the tolerances (USL+LSL/2) but this is not always the customer target.

Sometimes the customer may specify targeting the upper or lower end of the tolerance. This could be due to past experiences, part weight reduction, and many other reasons.

The value of Cpm is always > 0 and assumes normally distributed process output and uses the sample standard deviation calculation for sigma (within).

Cpm - capability indice


sample standard deviation

The links below explain other process capability indices.





Return to the MEASURE Phase

Return to the CONTROL Phase

Return to Basic Statistics

Return to Six-Sigma-Material Home Page

Click for a Password´╗┐

Six Sigma
Templates & Calculators
$14.95 USD

Six Sigma Modules

The following presentations are available to download

Click Here

Green Belt Program 1,000+ Slides
Basic Statistics
Process Mapping
Capability Studies
Cause & Effect Matrix
Multivariate Analysis
Central Limit Theorem
Confidence Intervals
Hypothesis Testing
T Tests
1-Way Anova Test
Chi-Square Test
Correlation and Regression
Control Plan

Six Sigma & Lean  Courses

Agile & Scrum Online Course