one industry expert stated that software today has eight err

one industry expert stated that software today has eight errors for every 1,000 lines of code. Assuming that there is only one opportunity to make an error for each line of code, at what sigma level is the coding processing operating? If eight errors are discovered, how many lines of code must there be for the process to be at a six-sigma level?

Solution

No. of lines = 1000
No. of errors = 6
% defect = (6/1000) x 100 = 0.6
% yield = 1 - % defect = 1 - 0.6 = 99.4%
Sigma = NORMSINV(% yield)+1.5 = 4.012

If No. of errors = 8

Defects per million for 6 sigma = 3.4
therefore, number of lines with 8 errors for six sigma would be

(8 x 1e6)/3.4 = 2352941 lines