Lynn,

First of all I'm glad that you like our newsletter. We try to make it interesting and educational. And based on what you say we have achieve our goal...

And oh my! You are so right about what you noticed in that sentence from the newsletter... I did not write that clearly enough...

Here is a better explanation:

**Six Sigma as a methodology:**
Six Sigma is a disciplined, data-driven approach and methodology that was originally developed by Motorola. The idea was to improve processes by eliminating defects. And a defect is defined as "nonconformity of a product or service to its specifications." Six Sigma at many organizations simply means a measure of quality that strives for near perfection.

**Six sigma as a measure of standard deviation:**
The Six Sigma methodology has a strong focus on numbers, describes quantitatively how a process is performing and uses standard deviations (or sigma) from the mean as a measure. For instance you might read that "Your process is performing to six sigma". This means that 99.99% of your output is without defect.

For the PMP exam you have to know the statistical percentages for 1, 2, 3 and 6 sigma:

1 sigma: 68.27% (68.2689492…)

2 sigma: 95.45% (95.4499736…)

3 sigma: 99.73% (99.7300204…)

6 sigma: 99.99% (99.9999998027…)

So you are absolutely correct in saying "six sigma" means six standard deviations above and below the mean. I will change the text in that newsletter so we don't give the wrong impression.