Six Sigma Defect Metrics

In this tutorial, you will learn about Six Sigma Defect metrics. Six Sigma is a methodology aimed at improving processes by identifying and removing causes of defects and minimizing variability.

Six Sigma defect metrics are key performance indicators used to measure the quality and capability of a process. They help organizations understand how well a process is performing in terms of producing defect-free outputs.

One of the key aspects of Six Sigma is measuring defects and process performance using a specific set of metrics. The defect metrics in Six Sigma are typically used to quantify the number of defects in a process and assess the process quality.

Let’s understand the important terms first:

Defect (D)

• A defect is any deviation from customer requirements or specifications.
• Example: A scratched phone screen, a billing error, or a late delivery.

Defective Unit (or Defective)

• A defective unit is an item or service that contains one or more defects.
• Note: One defective unit can have multiple defects.

Opportunity for Defect (O)

• An opportunity is a chance for a defect to occur in a unit.
• It must be something measurable and meaningful to the customer.
• Example: In a printed invoice, opportunities might include: correct customer name, correct amount, correct date, etc

Six Sigma Metrics

Some of the defect metrics are as follows:

• Proportion Defective
• Yield
• DPU(Defects Per Unit)
• DPO(Defects Per Opportunity)
• DPMO(Defects Per Million Opportunities)

Proportion Defective (p)

Proportion Defective(p) = Number Of Defective Units / Total Number of Production Units

Yield

Yield  = (Total Number of Product Units – Number Of Defective Units )/ Total Number of Production Units

or

Yield(Y) = 1 – p

Defects Per Unit( DPU)

Defects per unit(DPU)= Total Number Of Defective Units/ Total Number Of Production Units

Defects Per Opportunity(DPO)

Defects Per Opportunity(DPO) = Total Number Of Defective Units / (Total Number Of Production Units *  Number Of  Defect Opportunities Per Unit)

Defects Per Million Opportunities (DPMO)

Defects Per Million Opportunities(DPMO) = DPO * 1,000,000

 

That’s it. These metrics are foundational in the DMAIC (Define, Measure, Analyze, Improve, Control) methodology to baseline performance, identify improvement opportunities, and validate gains.