:) Hi,
When we move from a % (out of 100) based performance measure to finding defects out of 1mn, then we use the sigma calculations. Six Sigma level processeses have only 3.4 defects in 1mn opportunity. The DPMO (Defect per million opportunity) calculation shown in the excel sheet is reflecting the same. Alternatively you can go to isixsigma.com and calculate the DPMO also (based on defects found in your processes) and calculate the performance level in sigma (it is like measuring in milli seconds to differenciate the performance levels where if we measure in seconds then every thing may come equal) terms (instead of traditional % terms)