Predictions You Can Count On --Dickeson

Now we live in Sigma World, a non-linear world—a fractal world—the world where chaos prevails. Sigma is a calculation of one standard deviation from the average. We now believe that within three Sigmas on either side of the average, 99+ percent of all normal variation will occur. That's a stable range we can live with for predicting, for managing our business. If incidents occur outside those limits they're attributed to "special" causes that must be explained and eliminated to establish predictable stability and continuously improved performance.