PROCESS CAPABILITY
Step 10: Calculate the standard deviation and process capability
(x - μ) / σ
USL LSL 60
Cpk = USL - x̄ / 3σ or Cpk = x̄ - LSL / 3σ
p < 1, process control is poor
1 < Cp < 1.33, process control is satisfactory
Cp > 1.33, process control is good