Nonconforming Proportion

Since distributional analysis is not done with performance measures, and through-time stability may not be achieved, the use of process performance measures should be accompanied by examining the actual observed nonconforming proportion.

The total number of items examined and the number outside the specification limits are used to calculate the nonconforming proportion. This number is then translated into a parts per million (ppm) rate. The Nonconforming Proportion is calculated by the following formula.

Nonconforming Proportion -eqn