The main idea of usability is that a system shall be designed with (generalized) users’ psychology and physiology in mind, to make that system:

  • more efficient to use, so it takes less time to accomplish particular tasks
  • easier to learn
  • more satisfying to use


Definitions:

Capability of a product to be used by specified users to exchange information between a user and an interactive system via the user interface to complete the intended task. ISO-25010, v2022

The capacity of a system to provide a condition for its users to perform the tasks safely, effectively, and efficiently while enjoying the experience. Wikipedia

Typical Acceptance Criteria

Scenario Response Measures from [Bass et al.]

The system should:

  • provide the user with the features needed
  • anticipate the user’s needs
  • provide appropriate feedback to the user

The system’s response might be measured in one or more of the following:

  • task time
  • number of errors
  • learning time
  • ratio of learning time to task time
  • number of tasks accomplished
  • user satisfaction
  • gain of user knowledge
  • ratio of successful operations to total operations
  • amount of time or data lost when an error occurs

Bass et. al, 2022

What Stakeholders mean by usable

Stakeholder (potential) Expectation for usable
User see the criteria above. More specifically:
* functional-completeness
* accessibility
* correctness
* visual and behavioural consistency
* understandability
* ease-of-use
* functional-suitability
* learnability
* nice user-experience
(maybe even more)
Product-Owner -
Management -
Developer * understandable source-code and dependencies
* an appropriate technology-stack
* no (or at least predictable) side-effects when changing the system
Tester * testability
* predictable test behaviour
Admin * easy to deploy and install,
* installability
* deployability
Domain-Expert -
Others -

Qualities tagged with #usable

Requirements tagged with #usable