How
long
does it take to carry out some tasks?
How many and what kind of errors do people make in carrying out the
these tasks? How many tasks were successfully completed?
How long does it take for users to learn what actions are required to
perform their tasks?
How well do users maintain their knowledge and skills over given
periods of time?
How much did users like using verious aspects of the system?
Subjective satisfaction is positively correlated with behavioral
measures for usability, but not strongly (e.g., merely "aesthetic" or "cool" design is often perceived as easier to use, and has
a higher chance of being used, even when its objective usability is
low).