Usability Is a Measurable Outcome


Consumers say, “I want a product that is easy to use. Companies say, “Our product surpasses the competition in ease of use.” Human factors specialists apply knowledge and use methods to assure products achieve usability.

But what is “easy to use” exactly? And how do you measure it?

The International Organization for Standardization (ISO) defines usability as the “extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.” [ISO 9241-11 (1998)]

Getting more specific, those terms mean:

  • Effectiveness: The accuracy and completeness with which users achieve specified goals
  • Efficiency: The resources expended in relation to the accuracy and completeness with which users achieve goals (productivity)
  • Satisfaction: Freedom from discomfort and positive attitude to the use of the product
  • Context of use: Characteristics of the users, tasks, and the organizational and physical environments

Through those criteria, usability is a measureable outcome. It’s the result of a process that optimizes effectiveness, efficiency, and user satisfaction.

One such process is the user-centered design process.The distinguishing characteristic of the user-centered design process is the focus on the people who will use the product, service, or website: knowing the user, knowing the user’s needs, knowing how the user works, and evaluating if the product, service, website truly meets identified user needs.

Throughout the user-centered design process, there are appropriate methods to use that are aimed at addressing specific questions and aimed at supporting specific design objectives.

To learn more about user-centered design processes and the appropriate methods, contact us.