Proportion Nonconforming

Section 4 Process Capability

Lesson S04-02

Text: Section 4 pages 9 – 16

Duration: 27 minutes

Calculating the Proportion Nonconforming

Next, we explain a method for determining the proportion of nonconforming parts when the distribution of individuals is Normal. The procedure requires the use of the Standard Normal table (to avoid dealing with Calculus!) We will review the Standard Normal distribution and the table describing it.

The Standard Normal Distribution

The Standard Normal (or “Z” distribution as it is sometimes referred to) has the notable feature that the mean is zero and the standard deviation is 1. Thus, the Z scale is an indicator of the distance from average in number of standard deviations.

The 7-up Example

The Z Table used in this example is in the text in Section 4 page 14.

The Fuel Injector Example

How to Determine Probability with Excel

How to Determine Probability with Minitab