## Now Let’s start talking about 6sigma

Amrendra Roy

We have seen that variation is a part of life, we need to learn to live with it. At most we can make an effort to reduce it by using 6sigma tools.

This happens because you can’t control everything involved in any process. There are some uncontrollable factors known as “common causes” in six-sigma. For example

1. You are producing some part to be used in automobiles, there will be a variation in product specification as there will be wear and tear of machines, change of operators etc.

If we repeat any process 100 times, all product/output of the process would not have same specifications, it might happen all 100 are within the desired specification. If we plot a histogram of the product specification from a stabilized process, it would look like

We can see that maximum products would be clustered around the mean and as we move away from the mean, number of products decreases.

Width of the customer’s specification is analogous to garage’s width and the process variation is analogous to car’s width. If you don’t have proper control on your process (driving) you are going to crash your process (car) against the customer’s specifications (garage walls).

Now I feel that everyone agrees that variation is a part of life and we need to learn to cope with it. The only thing we can do is to minimize it by using some proven methodology so that whatever we are producing (product or services) should always meets customer’s specifications or should have enough safety margin. This proven methodology of reducing variability is called as 6sigma.

Car Parking & Six-Sigma

What’s the big deal, let’s rebuild the garage to fit the bigger car!

How the garage/car example and the six-sigma (6σ) process are related?

What do we mean by garage’s width = 12σ and car’s width = 6σ?