Chapter 11 - Usability Flashcards
what is usability
is concerned with how easy it is for the user to accomplish a a desired task and the kind of user support the system provides
5 areas of usability
- learning system features
- using the system efficiently
- minimizing the impact of errors
- adapting the system to user needs
- increasing confidence and satisfaction
general scenario: 1 value of source
end user
general scenario: 5 values for stimulus
- user tries to learn system
- user tries to use system efficiently
- user tries to minimize the impact of errors
- user tries to adapt the system
- user tries to configure the system
general scenario: 2 values for environment
run time
configuration time
general scenario: 1 value for artifact
system or portion of system with which the user is interacting
general scenario: 1 value for response
the system should either provide the user with the features needed or anticipate the user’s needs
general scenario: 4 value for response measure
- task time
- number of errors
- number of tasks accomplished
- user satisfaction
general scenario: 3 more values for response measure
- gain of user knowledge
- ratio of successful operations
- amount of time or data lost when error occurs
what is user initiative vs system initiative vs mixed initiative
describes in the human-computer pair takes the initiative in performing an action and how the interaction proceeds
2 categories of tactics
support user initiative
support system initiative
4 ways to support user initiative
- cancel
- undo
- pause/resume
- aggregate
meaning of “cancel”
the system must listen for a cancel request; the command being canceled must be terminated, resources must be freed, and collaborating components informed
meaning of “undo”
maintain a sufficient amount of information about the system state so that an earlier state may be restored at the user’s request
meaning of “pause/resume”
temporarily free resources so they may be re-allocated to other tasks
meaning of “aggregate”
ability to aggregate lower-level objects into a group, so that a user operation may be applied to the group
3 ways to support system initiative
- maintain task model
- maintain user model
- maintain system model
meaning of “maintain task model”
determines context so the system can have some idea of what the user is attempting and provide assistance
meaning of “maintain user model”
explicitly represents the user’s knowledge of the system, the user’s behavior in terms of expected response time etc.
meaning of “maintain system model”
system maintains an explicit model of itself. This is used to determine the expected system behavior so that appropriate feedback can be given to the user
