### What is Six Sigma?

Six-Sigma was developed by Motorola as a statistical focus on reducing quality defects. Six Sigma represents the mathematical calculation of 99.9996% perfection, equating to 3.4 dpmo (defects per million opportunities). Six Sigma improvement programs focus on the DMAIC process to achieve the Six-Sigma level of quality.

The term Six-Sigma, also referred to as 6 σ, is the statistical representation of the number of standard deviations away from the mean point in a bell curve, or what is known as the normal distribution. For non-statisticians, the bell curve is used to show the natural distribution of measurement points experienced in large populations (samples) of anything.

For example, height measurements of a 1000 people that are the same age and gender are recorded. The height of the majority of the people will be centered around the mean (average) of the population. Some of the people will be very short and others will be very tall, however, the main grouping of the people’s height will account for the majority of the group. This is the ‘normal distribution’. When graphed, the normal distribution will create a bell curve.