Defects per million opportunities (DPMO) - The average number of defects per unit observed during an average production run divided by the number of opportunities to make a defect on the product under study during that run normalized to one million. Defects Per Million Opportunities is synonymous with PPM. To convert DPU to DPMO, the calculation step is DPU/(opportunities/unit) * 1,000,000.
What Is DPO? What Is DPMO?
A unit of product can be defective if it contains one or more defects.A unit of product can have more than one opportunity to have a defect.
- Determine all the possible opportunities for problems
- Pare the list down by excluding rare events, grouping similar defect types, and avoiding the trivial
- Define opportunities consistently between different locations
Proportion Defective (p):
p = Number Of Defective Units / Total Number of Product Units
Yield ( Y1st-pass or Yfinal or RTY)
Y = 1 - p
The Yield proportion can converted to a sigma value using the Z tables
Defects Per Unit - DPU, or u in SPC
DPU = Number Of Defects / Total Number Of Product Units
The probability of getting 'r' defects in a sample having a given dpu rate
can be predicted with the Poisson Distribution
DPO = no. of defects / (no. of units X no. of defect opportunities per unit)
Defects Per Million Opportunities (DPMO, or PPM)
DPMO = dpo x 1,000,000
Defects Per Million Opportunities or DPMO can be then converted to sigma & equivalent Cp values
A couple Elsmar Cove discussion threads: How to define and Calculate the DPU, DPMO, Yield, Rolled Throughput Yield ( RTY) and How to decide the “U” to calcuate DPU and "opportunity" of DPMODefects per million opportunities (DPMO) Definition discussion thread