Usability
ECE 695
Alexander J. Quinn
3/21/2016
Today
Midterm
 Review 5 facets of usability

Five facets of usability

Learnability

Efficiency

Memorability

Errors

Satisfaction
learnability
“The system should be easy to learn so that
the user can begin working quickly.”
Credit: Jakob Nielsen, Usability Metrics: Tracking Interface Improvements, Interface, November 1996
efficiency
“The system should be efficient so that once
the user has learned it, high productivity is
possible.”
Credit: Jakob Nielsen, Usability Metrics: Tracking Interface Improvements, Interface, November 1996
memorability
“The system should be easy to use and
remember, so that the casual user can return
to it after not using it for a time and still know
how it works.”
Credit: Jakob Nielsen, Usability Metrics: Tracking Interface Improvements, Interface, November 1996
errors
“The system should have a low error rate, so
users will encounter few errors; those they do
encounter should be easy to recover from.
Further, catastrophic errors mus not occur.”
For our purposes, we will focus on human errors.
• Is it structured to mitigate inevitable limitations
in human cognition and memory?
• Can you gracefully recover from a human error?
Credit: Jakob Nielsen, Usability Metrics: Tracking Interface Improvements, Interface, November 1996
satisfaction
“The system should be pleasant to use.”
Credit: Jakob Nielsen, Usability Metrics: Tracking Interface Improvements, Interface, November 1996