Six Sigma Measures

1. COPQ (Cost of Poor Quality) - Appraisal Cost, Prevention Cost & Failure Cost


2. RTY (Rolled Throughput Yield) Cumulative yield = when data is defect rate or yield,
    RTY = FTY1*FTY2*FTY3*.....

3. FTY (First Time Yield) - Initial yield

4. Ynor (Normalized Yield) , Ynor = n FTY1*FTY2*…*FTYn

5. DPU (Defects per Unit) = no of defects / No of units

6. DPO (Defects per Opportunity) = no of defects / no of units * no of opportunity

7. DPMO (Defects per Million Opportunity = DPU * 1,000,000/ total opportunities per error

8. Process Capability Index -

(Cp = specification width/process width, Shift = Absolute value of (mean-target)

K = (shift)/0.5SW, Cpk = Cp (1-k))

(Pp, Ppk)

9.Sigma Level –

(a) In case of number of defects =

Calculate DPMO & find Z.st – value corresponding to DPMO from table

(b) In case of Yield =

Calculate yield by considering scrap & rework as defects

Find Z.st – value corresponding to number of NRFT per 1 million = (1-yield as ratio)*1,000,000 from table

(c) Calculate PPM from defect rate

PPM = (defect rate)*1,000,000

Find Z.st – value corresponding to DPMO which is equal to PPM from table