主题：六片藕的分法 -- 故园湾里

http://en.wikipedia.org/wiki/Six_sigma

单边和双边分点的意思可不是这样的，单边的时候

[edit] Sigma levels

Taking the 1.5 sigma shift into account, short-term sigma levels correspond to the following long-term DPMO values (one-sided):

One Sigma = 690,000 DPMO = 31% efficiency

Two Sigma = 308,000 DPMO = 69.2% efficiency

Three Sigma = 66,800 DPMO = 93.32% efficiency

Four Sigma = 6,210 DPMO = 99.379% efficiency

Five Sigma = 230 DPMO = 99.977% efficiency

Six Sigma = 3.4 DPMO = 99.9997% efficiency

俺学到 3 sigma的书比6 sigma早多啦

The particulars of the methodology were first formulated by Bill Smith at Motorola in 1986