In order for any process capability to accurately be calculated, one must properly define and quantify the process defect, unit and opportunity of a customer CTQ. This article defines the three terms, as well as provides examples.

By Kerri Simon

In order for any process capability to accurately be calculated, one must properly define and quantify the process defect, unit and opportunity. Every process should have definitions for defect, unit and opportunity. This article will define the defects, units and opportunities, as well as provide examples.

Start With The Customer

Before you can define your process defects, units and opportunities, you need to understand the needs of your customers. Voice of the Customer (Customer Needs, eSurveys, Focus Groups, Surveys) is the process of gathering customer comments/quotes and translating them into issues and specifications. From these comments, issues and specifications come the customer CTQ (Critical To Quality) – a product or service characteristic that must be met to satisfy a customer specification or requirement.

Define Your Product/Service Defects

A defect is defined as any part of a product or service that:

• does not meet customer specifications or requirements, or
• causes customer dissatisfaction, or
• does not fulfill the functional or physical requirements.

It should be noted that the term customer refers to both internal and external customers.

Define Your Product/Service Units

A unit is something that can be quantified by a customer. It is a measurable and observable output of your business process. It may manifest itself as a physical unit or, if a service, it may have specific start and stop points.

Define Your Product/Service Opportunities

Simply stated, opportunities are the total number of chances per unit to have a defect. Each opportunity must be independent of other opportunities and, like a unit, must be measurable and observable. The final requirement of an opportunity is that it directly relates to the customer CTQ (see Start With The Customer above). The total count of opportunities indicates the complexity of a product or service.

CTQ Examples Including Defect, Unit and Opportunity

Area: Call Center
Customer Quote: ‘I consistently wait too long to speak to a representative.’
CTQ Name: Representative Responsiveness
CTQ Measure: Time on hold (seconds)
CTQ Specification: Less than 60 seconds from call connection to the automated response system
Defect: Calls with hold time equal and greater than 60 seconds
Unit: Call
Opportunity: 1 per call

	Calculate Your Sigma (Plug in the values below to calculate Sigma)
	Defects: 263 calls
	Units: 21,501 calls
	Opportunities: 1 per call
	Sigma: 3.75

Area: Book Publisher
Customer Quote: ‘I can’t stand typos in books I purchase.’
CTQ Name: Typographic Quality
CTQ Measure: Number of typographical mistakes
CTQ Specification: Zero typographical mistakes
Defect: Any typographical mistakes
Unit: A word
Opportunity: Words per book

	Calculate Your Sigma (Plug in the values below to calculate Sigma)
	Defects: 2 typographical mistakes
	Units: 100,000 (500 words/page x 200 pages/book)
	Opportunities: 1 per word
	Sigma: 5.61

Area: Printed Circuit Board Manufacturing
Customer Quote: ‘Boards must work when I plug them in.’
CTQ Name: Board Functionality
CTQ Measure: Non-functioning or improperly functioning boards
CTQ Specification: All boards function properly (a board wil not function properly if any individual component is bad)
Defect: Any non-functioning or improperly functioning board
Unit: A board
Opportunity: Total number of parts plus solder points

	Calculate Your Sigma (Plug in the values below to calculate Sigma)
	Defects: 18 boards
	Units: 1,000 boards
	Opportunities: 58 (1 board + 13 resistors + 4 capacitors + 2 diodes + 38 solder points)
	Sigma: 4.92