Directory of ITIL, ITSM & security services  
& software. A launch pad for the  
IT infrastructure library (ITIL) & ITSM  

 Directory of Software & Services for ITIL. The Six Sigma Methodology Contact Us Front Page

Related Process Models - The Six Sigma Methodology

A classic definition: "Six Sigma is a process-focused methodology designed to improve business performance through improving specific areas of a strategic business processes.". From this alone it is clear why there are a number of parallels with ITIL, although six sigma of course isn't restricted to information technology.

Sigma is a symbol meaning how much deviation exists in a set of data - sometimes called a bell curve, or a standard normal distribution. In a standard normal distribution, 50% of the values lie above the mean (average) and 50% of the values lie below. In Statistics we take it a step further and delineate certain data points within that timeline.

Six Sigma Methodology

The diagram may look tricky to read, but in simple language: Consider that you run a pizza delivery business and you set a target of delivering pizza’s within 25 minutes of receiving the order. If you achieve that 68% of the time, you are running at 1 Sigma. If you achieve it 99.9997% of the time then you are at 6 Sigma (or you are late on average only 3.4 times out of every one million orders).

That is fundamentally how six sigma measures quality. It measures the Variance and does not rely on the Mean.

It is argued that all too often businesses base their performance on a mean, or average-based measure, of the recent past. However, reality is that customers DON'T judge businesses on averages. They actually experience the variance in each and every transaction or purchase.

Customers also value consistent and predictable business processes and products that deliver high levels of quality. Six Sigma focuses first on reducing variation, and then on improving process capability.


It is certainly an interesting approach, and is well tried and tested. Since it was developed by Motorola in the eighties it has been adopted by more and more corporations and major organizations. It is now extremely widely used and has resulted in substantial and demonstrable improvements in organizations of all shapes and sizes.


Clearly this is a substanital and complex method, and one that we cannot do justice to on a single page of an ITIL portal. If you wish to explore Six Sigma in more depth therefore, we would direct you to the: Six Sigma Management Kit. This commercial tool kit was produced specifically to introduce Six Sigma, and to provide a number of basic support resources.


Copyright © 1993-2003 BC Associates