Six Sigma is associated with reducing variation by using how many standard deviations from the mean?

Six Sigma is associated with reducing variation by using how many standard deviations from the mean?

• A. 4
• B. 5
• C. 6
• D. 7

Answer: (C)

Six Sigma quality is defined by the process mean being at least six standard deviations away from the nearest specification limit, which keeps variation tightly under control. In practical terms, that level of separation means the vast majority of outputs fall within tolerance, yielding a very low defect rate—about 3.4 defects per million opportunities when a typical 1.5 sigma shift is considered. So the number of standard deviations associated with Six Sigma is six.

Six Sigma quality is defined by the process mean being at least six standard deviations away from the nearest specification limit, which keeps variation tightly under control. In practical terms, that level of separation means the vast majority of outputs fall within tolerance, yielding a very low defect rate—about 3.4 defects per million opportunities when a typical 1.5 sigma shift is considered. So the number of standard deviations associated with Six Sigma is six.