DPMO

DPMO is the abbreviation for defects per million opportunities.

It is a metric commonly used in six sigma. Presumably, if you are engaged in an active process improvement effort, you will have made (or will eventually) make significant improvements to your quality.

For that reason, it can be difficult to conceptualize small decimals, like .003 or .00045. It is easier for most people to compare 3000 to 450.

To calculate DPMO, divide the number of defects by the total number of opportunities for a defect, and multiply by 1,000,000. The total number of opportunities is the number of units times the number of defect opportunities per unit.

DPMO= [Defects / (defect opportunities per unit x number of units)] x 1,000,000

As an example, let’s say you sampled 100 items, each with 20 opportunities for mistakes. These could be fields in a data entry form, or they could be items on an inspection checklist on a physical product.

Either way, you end up with 2000 opportunities for failures. If you have 17 failures, you would end up with

(17/[10×20]) X 1,000,000 = 8,500 DPMO

Now, while this gives an overall view of quality, it does not reveal the actual number of items with at least one defect. For example, you might have one really poorly done form with 14 errors on it, and two others with 1 and 2 errors, for a 97% yield (percent of items that pass), or there could be 17 items with one defect each for an 83% yield.

The 8,500 DPMO number, though, gives you a good view of internal quality, even if it doesn’t give the full picture of what is reaching the customer.