Anticlue

Six Sigma: Operational Definitions

Once you decided to collect data and measure performance, remember precise definitions are needed for what you are measuring. Its just not a good place to be to have gone through the collection and measurement process, then come to the realization you are comparing apples to arm chairs. Clarification of what defects count in a process or service is important, but deciding what is meant by each term has the same level of importance.

An operational definition is a specific description of the defect, process, product and/or service to be measured. The operational definition is agreed to by all and an exact consistent definition. As with the every quality process, controls and cross-check are used to assure it is valid. These are four criteria used in validating an operational definition.

1. The requirement to be measured must be agreed upon - The requirement being measured is the process, product, or service the team wants to improve. A requirement might be to provide a constant system availability. All the words in the phrase should be clear and understandable.
2. The method of measurement must be agreed upon - The method used to measure the requirement is typically expressed quantitatively so it will not be misunderstood. To measure and assure system availability, the method might be to gather all times the system is unavailable.
3. There must be agreement on what the definition will not include - The team should exclude from its operational definition anything that prevents it from being used consistently. For example, the definition for system availability might exclude the nightly processing when the system is unavailable to its users. Agreeing on what will not be included in the measurement of an operational definition is nearly as important as agreeing on what will be included.
4. Customers must agree with the team that the operational definition is appropriate- The customers of the process, product, or service must agree with the team on the appropriateness of the definition. To the customers, system availability might only mean during working hours.

The truth of the matter is that clarification is important, and vetted clarification has even a stronger need. The operational definition that results from validating through the four criteria has significance and is measurable. After all you can’t manage if you don’t know what you are measuring.