I was just wondering what does the word Six Sigma stand for?
Six Sigma is a management approach for focusing resources on improvements to cost, scheduling and/or quality concerns within an organization. An effective Six Sigma program will be led by management, with project teams deployed in three to six month assignments to address specific issues aligned with the strategic objectives of the organization.
The term Six Sigma originated at Motorola in their pursuit of the Malcolm Baldrige quality award. Sigma is the term statisticians use for standard deviation, the amount of variation in a process metric. For example, your customers may desire your response time for answering customer service questions to be less than ten minutes. After collecting some response time data from your process, we can calculate an average response time, and the standard deviation of the response time. If your average response time is eight minutes, with a standard deviation of one minute, the customer requirement (ten minutes) is only two standard deviations (two sigma) from the mean (or average) of eight minutes, implying that it is quite common for the response time to exceed the ten minute requirement. When this process has been improved to a Six Sigma level of performance, the average response time will be shorter, and perhaps the standard deviation also smaller, such that there is only a very remote chance (3.4 out of million) that the response time would exceed ten minutes.
See also: Sigma Level
Learn more about the Lean Six Sigma principles and tools for process excellence in Six Sigma Demystified (2011, McGraw-Hill) by Paul Keller, in his online Lean Six Sigma DMAIC short course ($249), or his online Green Belt certification course ($499).