Usability Engineering

Jakob Nielsen, topic-ux · 1994

Excerpts

Typical quantifiable usability measurements include:

  • The time users take to complete a specific task.
  • The number of tasks (or the proportion of a larger task) of various kinds that can be completed within a given time limit.
  • The ratio between successful interactions and errors.
  • The time spent recovering from errors.
  • The number of user errors.
  • The number of immediately subsequent erroneous actions.
  • The number of commands or other features that were utilized by the user (either the absolute number of commands issued or the number of different commands and features used).
  • The number of commands or other features that were never used by the user.
  • The number of system features the user can remember during a debriefing after the test.
  • The frequency of use of the manuals and/or the help system, and the time spent using these system elements.
  • How frequently the manual and/or help system solved the user’s problem.
  • The proportion of user statements during the test that were positive versus critical toward the system.
  • The number of times the user expresses clear frustration (or clear joy).
  • The proportion of users who say that they would prefer using the system over some specified competitor.
  • The number of times the user had to work around an unsolvable problem.
  • The proportion of users using efficient working strategies compared to the users who use inefficient strategies (in case there are multiple ways of performing the tasks).
  • The amount of “dead” time when the user is not interacting with the system. The system can be instrumented to distinguish between two kinds of dead time: response-time delays where the user is waiting for the system, and thinking-time delays where the system is waiting for the user. These two kinds of dead time should obviously be approached in different ways.
  • The number of times the user is sidetracked from focusing on the real task.

Bib

@book{nielsen-usability-engineering,
  title={Usability engineering},
  author={Nielsen, Jakob},
  year={1994},
  publisher={Morgan Kaufmann}
}