Target Z, Zupper, and Zlower formulas | Formulas and tables

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Target Z, Z_upper, and Z_lowerformulas

Target Z

Z_upper

Zupper formula

Z_lower

Zlower formula

Where:

= the mean of the X-bars
T = specification target
Sigma is an estimated sigma or sigma of the individual values, depending on how the histogram
is configured or whether you are calculating Cpk (estimated) or Ppk (actual).