DPMO

Acronym for Defects per Million Opportunites.

It is a popular metric used in Six Sigma to measure the performance of a process. If a process achieves Six Sigma level quality, it equates to a 3.4 DPMO. The actual DPMO for a Six Sigma process is 0.002 DPMO, but is adjusted with the Motorola Shift by 1.5 sigma to account for long term variation in a process.

A defect can be defined as a nonconformance of a quality characteristic (e.g. strength, weight, response time, visual criteria) to its specification.

As an example in healthcare, if 500 prescriptions are reviewed, and there are 5 possible ways (opportunities) to make an error (defect) in each prescription, then there are 2,500 (500 x 5) possible errors that could be made.

The 5 opportunities for error could be:

• Wrong medication listed
• Wrong patient ID number
• Wrong date/time
• Wrong dosage amount
• Wrong route of administration identified (suppository, oral, topical, etc)

If 35 defects are found (there may be more than one on in a single medical record), then DPMO is calculated as:

DPMO = (# of defects x 1,000,000) / (# of items x # of opportunities per item)) = (35 x 1,000,000) / (500 x 5)

DPMO = 35,000,000 / 2500 = 14,000

Therefore, for every one million opportunities there are to make a medical record error, there will be 14,000 defects found.

Links

• Wikipedia: Defects per million opportunities
• Driving Quality Improvement with DPMO: A Roadmap to Process Excellence (iSixSigma)