Understanding of 6 Sigma

1) Numerical meaning of 6 Sigma

We have learnt 6 Sigma and Sigma level before.
Strictly saying, 6 sigma is 6 sigma level. The bigger sigma level is, the smaller standard deviation is and our work accomplishment is high.
If so, we need a goal and that can be level 6 in sigma.
Please look at this chart showing percentage and PPM of each sigma level.

σ Level	%	PPM
6	99.99966	3.4
5	99.9767	233
4	99.379	6,210
3	93.3193	66,807
2	69.1463	308,537
	Good product	Defect

Summary
- If sigma level is 6, the numerical value is almost perfect. This means only 3 or 4 times out of one million times are the customer complaints, that is 3.4 ppm (parts per million).
- In a philosophical side, 3.4 ppm is defined as ‘perfect’ or ‘zero defect’.

2) Comparison between 99% of accuracy and 6σ Level

Talking about the accuracy, normally people count on 99%.
However, that 99% of accuracy is very risky according to the chart below.

	99% of accuracy (4∂ level)	6σ Level
Delivering 300,000 letters	mistakenly delivered : 3,000 letters	1
Booting 500,000 computers	not booted : 4,100 sets	less than 2 sets
Monthly accounting due for 500 years	unbalanced between income and expense : 60months	only 0.018 month
On-air hour for a week	banned : 1.68 hours	only 1.8 sec

(The Six Sigma Way - Mc Graw Hill, published in 2000)

99% of accuracy is level 4, we say, sigma 4.
Our final goal is 6 sigma, that is level 6, 99% of accuracy is still risky.

3) Origin of 6 Sigma
Now is time to learn the origin of 6 sigma.
Motorola has started 6 sigma activity for the first and the core of marketing strategy was " Technology".
Based on the company's technology, they show the world's first product ahead of competitors to occupy the market.
That was a very aggressive marketing strategy.
In 1980's, the defect rate of Motorola's wireless beeper, on the peak, was very high enough to cause customer complaints accordingly.
After researching the high defect rate, Motorola found it was from the factory originally, not from the customers. Actually the factory modifies or repairs the defected products to ship out. Most of them cause the problem again.
Since then, Motorola confirmed "no defect rate" in order to provide customers with perfect products.
For this, each unit process should put out the perfect products and the goal is 6 Sigma level.

Therefore, the less we reduce a hidden factory, the higher we provide customers with good products (this is called a cumulative nonstop rate). Finally we get the benefit to reduce the cost internally.
On of the important maters Motorola considered in 6 Sigma activity was benchmarking.
They benchmarked the core competency from their contractors and even Benetton that is not related to their business. This suggests how important benchmarking is.
Later then, the Reagan administration has established Malcolm Baldrige Award in order to encourag the policy to secure the competitiveness of American enterprises through the quality improvement. Motorola took the role to propagate 6 Sigma Activity in the U.S. by that chance.
In 1997, Sony judged “Penalty and memory are not the way to catch up with the U.S.” so that they have actively accepted 6 Sigma Activity instead of their TQC activity.

4) Benefit of 6 Sigma Activity
5) Process of 6 Sigma improvement activity

The first step of innovation and improvement activity in the organization is to select the process with the biggest variation of output.
Thus, we need to analyze the process through Statistical Thinking, that is, "All work occurs in a system of interconnected processes".
Then we should confirm the size of variation and its cause existed in processes through data.
Finally, we must optimize the process in the organization by improving and solving causes.

In summary of it,
Improvement activity of 6 sigma is divided into 5 steps in process like the below ;

Step 1 : to define which process has the most variation. (Define) Step 2 : to measure the size of variation in process. (Mesurement) Step 3 : to analyze the cause of variation. (Analysis) Step 4 : to remove causes to improve process. (Improvement) Step 5 : to manage the variation of improved process. (Control)

6) 6 Sigma in system

Now we will check 6 sigma in system.
The basic business process in the company could be ; R&D, manufacturing, promotion.
Integrating these with 6 sigma activity will be as follows ;

Let’s take a look at more in detail ;
Through 6 sigma activity of R&D, we can produce the theoretical quality as the drawings. This can be an input in terms of manufacturing.
Manufacturing process needs to change the theoretical quality into the actual one.
The smaller the gap between them is, the higher the product quality is.

The actual quality in manufacturing can be an input in promotion. Its role is to improve sales promotion to produce management outcome.

Now we can see 6 sigma activity is to optimize the whole process in the terms of the whole organization(company), not to improve the part of company.
Each process should optimize itself and enhance the synergy effect using feedback. This will lead the company to maximize the management outcome.