A change in the quality level from 3-sigma to 4-sigma represents a five-fold improvement.

Question

Quizplus · Accepted Answer

A change from 3-sigma to 4-sigma means the process will have fewer defects and a higher level of quality, which represents a significant improvement. The difference between the two sigma levels corresponds to a reduction of defects from 66,807 ppm (parts per million) to 6,210 ppm, which is about a five-fold improvement.

A Change in the Quality Level from 3-Sigma to 4-Sigma