DPU is the average number of defects per unit. The ratio of defects to unit is the universal measure of quality.
D: number of Defects
U: number of Units
DPU may be estimated if the Throughput Yield (also called First Pass Yield) is known:
Take this table shown below as an example.
Ten nails were produced at a manufacturing facility and each nail has five ways (opportunities) it can be defective. If any one of the five characteristics fails, then the entire nail is considered defective.
There is a possibility of 50 total defects if each nail had all five characteristics (opportunities) fail.
The total number of defects (D) is 2+1+3+2+3+4+2+2 = 19.
The number of defectives is 8.
8 out of 10 nails contained one or more defects qualifying them as defective.
From the table above:
D = 19 total defects were found
U = 10 units (nails)
DPU = 1.9 defects per nail
If all these defects could come from a SINGLE process (not in reality for this case, these types of defects occur from different operations), rearranging the formula above the TPY
Several metrics are related such as the following below. You should be able to calculate all of them as preparation for a Six Sigma certification exam.
TOP - Total Opportunities
DPO - Defects Per Opportunity
DPMO - Defects Per Million Opportunities
Click here to get a DPMO and Six Sigma Calculator that also computes DPO and DPU and allows you to analyze various scenarios and the impact on the metrics.
Keep in mind PPM and DPMO are not the same term
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