Operational Definition

Custom Search

Get Free Six Sigma Tools Here

What Is It...?

An Operational Definition gives communicable meaning to a concept by specifying how the concept is measured and applied within a particular set of circumstances. This definition highlights two important things -

  • It gives a precise meaning to the spoken or written word, forming a "common language" between two or more people.
  • It defines how a word or phrase is used when it is applied in a specific context.

This implies that words may have different meanings when used in different situations. For example, the Operational Definition of "ready" used in sandwich shop would be very different from the one applied in a hospital.

It isn't a quality improvement "tool" in the same sense that Affinity Diagrams, Flowcharts, Pareto Charts, and Histograms are. However, they are the vital underpinning that helps you use all of these other tools successfully.

Why Use It

An Operational Definition puts workable meaning into our everyday terminology. Words such as "good," "reliable," "defect," and "okay" can have many meanings unless they are defined in specific terms that apply in particular circumstances. 

As an example, in the absence of definition, the term "squared away" might mean one thing to an Executive immediately prior to the visit of a VIP, and quite another to a young worker involved in preparing for the visit but anxious to start a weekend. 

However, if "squared away" were operationally defined among all of those getting ready for the VIP, the term would mean the same thing to the Executive and the worker.

To communicate effectively and avoid misinterpretations, team members, data collectors, and both internal and external customers and suppliers must use the same Operational Definition for the same concept.

Misunderstandings waste time; but worse, they add variation to your process. Consequently, it is vitally important to develop Operational Definitions at each step of a process.

Core Elements

An Operational Definition has three core elements that help you to apply it:

  1. Criterion: The standard against which to evaluate the results of the test.
  2. Test: A specific procedure for measuring a characteristic.
  3. Decision: The determination as to whether the test results show that the characteristic meets the criterion.

Developing an Operational Definition

Here's an example from Deming's discussions. It shows how you can establish one or more criteria, measure, and reach a decision:

What is meant when a blanket label says "50 percent wool"?

  • One interpretation might be that one-half of the area of the blanket is wool and the other half is another material, such as cotton.
  • Another interpretation might be that the wool is evenly dispersed throughout the entire blanket.
  • Still another interpretation might be that the blanket is two-ply, with one side made entirely of wool and the other side made of cotton.

In the absence of more information, any of these definitions could be "correct." But what do you want your blanket to be like? You won't get what you want unless you develop an Operational Definition of what is meant by the term "50 percent wool."


Criterion: First, you need to set the criterion or standard for calling the blanket "50 percent wool." In this example, the criteria are that the wool and cotton fibers are evenly distributed throughout the blanket and the wool comprises half the total weight of the blanket. Other criteria could have been used, such as the number of threads of wool compared to the number of threads of cotton.

Test: After you have decided on the criteria for "50 percent wool," you must set up a test procedure to determine whether the blanket meets the criteria. In this example, the decision was made to use a quantitative test in which ten 2-inch-by-2-inch squares were cut from specified areas in sample blankets. These swatches were handed over to a laboratory technician to analyze and measure the proportion of wool by weight.

Decision: Now you must make a decision. When the laboratory technician has performed the test on the samples and presented you with the data, it becomes a yes-or-no decision: Did the results of the test meet the criteria?

“An OD is one that people can do business with....It must be communicable, with the same meaning to vendor as to purchaser, same meaning yesterday and today...” 

A correctly formulated definition enables all of the people involved in a transaction to use and understand a term in exactly the same way every time.

Here's another simple example - What is a clean table?

If you are using the table as a workbench, then clean may only mean that it is free of clutter. On the other hand, if it is a lunch table, you would want some level of cleanliness which is achieved by using a mild detergent. If it is an operating room table, it would have to be antiseptically clean to prevent the spread of infection. The

The definition of clean is quite different for each of these situations, so you can see that context is important.

From Operational Definition to Six Sigma Process

Recent Articles

  1. Quality Control Plan - Simple Method To Create Effective Plans

    May 10, 16 09:24 PM

    A Quality Control Plan is a documented description of the activities needed to control a process or product. The objective of a QCP is to minimize variation.

    Read More

  2. Get Free Six Sigma Tools

    May 10, 16 08:49 PM

    The Largest Collection of Free Six Sigma Tools and Training on the Web!

    Read More

  3. Weibull Distribution

    May 10, 16 07:28 PM

    The Weibull distribution is applicable to make population predictions around a wide variety of patterns of variation.

    Read More