Refer to Example 10.13. To what value must the process standard deviation be reduced in order for the process to attain six-sigma quality?
To attain six-sigma quality, the value of C_{p} must be at least 2.0. The value of 𝜎 for which this occurs is found by setting C_{p} = 2.0 and solving for 𝜎. We obtain
2.0 = \frac{52\ −\ 48}{6\sigma}
from which 𝜎 = 0.33.