Utility
- Utility
- the quality factor representing the degree to which a
system, software
application, or one of their
components can be effectively utilized
As illustrated in the preceding figure, Utility is part of the following inheritance hierarchy:
The typical responsibilities of utility are to:
- Model the degree to which a system, software application or component can be effectively utilized.
- Support the analysis and specification of
utility requirements.
Utility can be decomposed into the following subfactors:
Utility is typically measured in terms of:
- Effectiveness:
- Unassisted Task Completion Rate
- The percentage of users who successfully and completely perform their task without requiring assistance
from either the product (i.e., system, software application, or component) or a human expert to continue
- Product Assisted Task Completion Rate
- The percentage of users who successfully and completely perform their task, even if they required
assistence provided by the product (e.g., online help function) to continue
- Human Assisted Task Completion Rate
- The percentage of users who successfully and completely perform their task, even if they required
assistence provided by a human to continue
- Efficiency:
- Mean Task Completing Time
- The mean time typical users take to complete a given task
- Relative Task Completing Time
- The ratio of the mean time users take to complete a given task to the mean time experts take to complete
the same task
- Task Completing Time / Mean Time-On-Task
- The mean time typical users take to complete a given task divided by the mean time they spend on task
- Satisfaction:
- Mean Subjective Ease of Use Rating
- The mean ease of use rating users give on questionnaire
- Mean Subjective Satisfaction Rating
- The mean satisfaction rating users give on questionnaire
- Mean Subjective Usefulness Rating
- The mean usefulness rating users give on questionnaire
Typical mechanisms for achieving utility include:
- Help Function
- Function Keys
- Macros
The following guidelines have been found to be useful with respect to utility:
