Chapter 11 - Usability

Question 1

what is usability

Answer 1

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

Question 2

5 areas of usability

Answer 2

• learning system features
• using the system efficiently
• minimizing the impact of errors
• adapting the system to user needs
• increasing confidence and satisfaction

Question 3

general scenario: 1 value of source

Answer 3

end user

Question 4

general scenario: 5 values for stimulus

Answer 4

• 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

Question 5

general scenario: 2 values for environment

Answer 5

run time

configuration time

Question 6

general scenario: 1 value for artifact

Answer 6

system or portion of system with which the user is interacting

Question 7

general scenario: 1 value for response

Answer 7

the system should either provide the user with the features needed or anticipate the user’s needs

Question 8

general scenario: 4 value for response measure

Answer 8

• task time
• number of errors
• number of tasks accomplished
• user satisfaction

Question 9

general scenario: 3 more values for response measure

Answer 9

• gain of user knowledge
• ratio of successful operations
• amount of time or data lost when error occurs

Question 10

what is user initiative vs system initiative vs mixed initiative

Answer 10

describes in the human-computer pair takes the initiative in performing an action and how the interaction proceeds

Question 11

2 categories of tactics

Answer 11

support user initiative

support system initiative

Question 12

4 ways to support user initiative

Answer 12

• cancel
• undo
• pause/resume
• aggregate

Question 13

meaning of “cancel”

Answer 13

the system must listen for a cancel request; the command being canceled must be terminated, resources must be freed, and collaborating components informed

Question 14

meaning of “undo”

Answer 14

maintain a sufficient amount of information about the system state so that an earlier state may be restored at the user’s request

Question 15

meaning of “pause/resume”

Answer 15

temporarily free resources so they may be re-allocated to other tasks

Question 16

meaning of “aggregate”

Answer 16

ability to aggregate lower-level objects into a group, so that a user operation may be applied to the group

Question 17

3 ways to support system initiative

Answer 17

• maintain task model
• maintain user model
• maintain system model

Question 18

meaning of “maintain task model”

Answer 18

determines context so the system can have some idea of what the user is attempting and provide assistance

Question 19

meaning of “maintain user model”

Answer 19

explicitly represents the user’s knowledge of the system, the user’s behavior in terms of expected response time etc.

Question 20

meaning of “maintain system model”

Answer 20

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