Question

A manager states that her process is really working well. Out of 1,500 parts, 1,477 were produced free of a particular defect and passed inspection. Based upon Six Sigma theory, how would you rate this performance, other things being equal?

Short answer

Six sigma theories is a quality management theory that is used to help businesses in improving their current processes, their products, or services by eliminating and determining the defects.

Step-by-step solution

About the DPMO

The managers can define the performance of the product by using this DPMO method which means “defects per million” units.

Metric DPMOcan be calculated using the formula:

$\mathrm{DPMO}=\frac{\mathrm{Total}\mathrm{number}\mathrm{of}\mathrm{defects}\mathrm{in}\mathrm{a}\mathrm{sample}}{\mathrm{Number}\mathrm{of}\mathrm{opportunities}\mathrm{of}\mathrm{per}\mathrm{error}\mathrm{per}\mathrm{unit}}\times \mathrm{Number}\mathrm{of}\mathrm{units}\times 1,000,000$

As per the Six sigma theory, rate the performance

Put the values in the above formula:

$=\frac{1500-1477}{1\times 1500}\times 1,000,000$

$=\frac{23}{1500}$

= 15, 333, 33 is the defect rate of the process

$\begin{array}{l}\mathrm{Defectrate}=\frac{\mathrm{No}.\mathrm{of}\mathrm{defects}}{\mathrm{No}.\mathrm{of}\mathrm{units}}\times 100\\ =\frac{1500-1477}{1500}\times 100\\ =\frac{23}{1500}\times 100\\ =1.53\%\mathrm{six}\mathrm{sigma}\end{array}$

The theory focuses on achieving of 3.4 defects per million (DPM). However, in this case, the process performance of the process is not as good as said by the manager.