WEB
USABILITY OVERVIEW
(For
THE Complete Web Usability Site - See Jakob Nielsen's:
Use It)
Usability
assesses how easy user interfaces are to use. The word "usability" also
refers to methods for improving ease-of-use during the design
process.
The most
basic and useful is method for studying usability is
user testing, which has three components:
- Getting
representative users.
- Ask
the users to perform representative tasks with
the design.
- Observe
what the users do, where they succeed, and where
they have difficulties with the user interface. Shut
up and let the users do the talking.
Usability has five components:
- Learnability:
How easy is it for users to accomplish basic tasks
the first time they encounter the design?
- Efficiency:
Once users have learned the design, how quickly
can they perform tasks?
- Memorability:
When users return to the design after a period
of not using it, how easily can they reestablish proficiency?
- Errors:
How many errors do users make, how severe are these
errors, and how easily can they recover from the errors?
- Satisfaction:
How pleasant is it to use the design?
A key attribute is utility, which refers to the design's functionality:
Does it do what users need? Usability and utility are equally
important: It matters little that something is easy if it's
not what you want. On the Web, usability is a necessary condition
for survival.
- If a website
is difficult to use, people leave.
- If the
homepage fails to clearly state what a company offers
and what users can do on the site, people leave.
- If users
get lost on a website, they leave.
- If a website's
information is hard to read or doesn't answer users'
key questions, they leave.
There
are plenty of other websites available; leaving is
the first line of defense when users encounter a difficulty.
Usability
plays a role in each stage of the design process.
- Before
starting the new design, test the old design to
identify the good parts that you should keep or emphasize,
and the bad parts that give users trouble.
- Test
competitors' designs to get cheap data on a range
of alternative interfaces that have similar features
to your own.
- Conduct
a field study to see how users behave in their
natural habitat.
- Make
paper prototypes of one or more new design ideas
and test them. The less time you invest in these design
ideas the better, because you'll need to change them
all based on the test results.
- Refine
the design ideas that test best through multiple
iterations, gradually moving from low-fidelity prototyping
to high-fidelity representations that run on the computer.
Test each iteration.
- Inspect
the design relative to established usability guidelines,
whether from our own earlier studies or published research.
- Once
we decide on and implement the final design, test
it again. Subtle usability problems always creep in
during implementation.
The only way to a high-quality user experience is to start
user testing early in the design process and to keep testing
every step of the way. |
