
Provides
a basic overview of and general information about usability.

What
Is Usability?
Usability is the measure
of the quality of a user's experience when interacting with a product
or system whether a Web site, a software application, mobile
technology, or any user-operated device.
Usability is a combination
of factors that affect the user's experience with the product or system,
including:
Ease
of learning |
How fast
can a user who has never seen the user interface before learn
it sufficiently well to accomplish basic tasks?
|
Efficiency
of use |
Once an
experienced user has learned to use the system, how fast can
he or she accomplish tasks?
|
Memorability |
If
a user has used the system before, can he or she remember enough
to use it effectively the next time or does the user have to start
over again learning everything?
|
Error
frequency and severity
|
How
often do users make errors while using the system, how serious
are these errors, and how do users recover from these errors?
|
Subjective
satisfaction |
How much
does the user like using the system? |
Links to Related Articles
Usability
and the Web: An Overview, by George Murray and Tania Costanzo,
at the National Library of Canada,
http://www.nlc-bnc.ca/9/1/p1-260-e.html
What
Is Usability?, by Environmental Systems Research Institute, Inc.,
http://www.esri.com/software/usability/whatisusability.html
Why
Is Usability Important?
Research by User
Interface Engineering, Inc., shows that people cannot find the information
they seek on Web sites about 60% of the time. This can lead to wasted
time, reduced productivity, increased frustration, and loss of repeat
visits and money.
Other sources report:
- "There are about
43 million Web sites, and no one knows which ones are usable. The
best sites we've found are usable only 42 percent of the time, and
none that we have studied are usable a majority of the time ...."
- Studies by Forrester
Research estimate several costs of bad site design. The two most striking
are:
Losing
approximately 50% of the potential sales from a site as people can't
find what they need
Losing
repeat visits from 40% of the users who do not return to a site
when their first visit resulted in a negative experience
- Site design guru
Jakob Nielsen reports:
"Studies of
user behavior on the Web find a low tolerance for difficult designs
or slow sites. People don't want to wait. And they don't want to
learn how to use a home page. There's no such thing as a training
class or a manual for a Web site. People have to be able to grasp
the functioning of the site immediately after scanning the home
page for a few seconds at most."
Links to Related Articles
Mazed
and Confused, Sari Kalin, CIO WebBusiness, http://www.cio.com/archive/webbusiness/040199_use.html
Failure
of Corporate Websites, Jakob Nielsen, Alertbox, http://www.useit.com/alertbox/981018.html
Web-Site
Usability: Usability On The Web Isn't A Luxury, Jakob Nielsen
and Donald A. Norman, in InformationWeek, http://www.informationweek.com/773/web.htm
What
Is the Difference Between Usability Engineering and Usability Testing?
Usability engineering
is a methodical approach to producing a Web site or any user interface.
It is a practical and systematic way to deliver a product that works
for users. Usability engineering involves several methods, each applied
at appropriate times, including gathering requirements, developing and
testing prototypes, evaluating design alternatives, analyzing usability
problems, proposing solutions, and testing a site (or other interface)
with users.
Usability testing
is part of the process of usability engineering. Usability testing includes
a range of methods for having users try out a site (or other system).
In a typical usability test, users perform a variety of tasks with a
prototype (or other system) while observers record notes on what each
user does and says. Typical tests are conducted with one user at a time
or two users working together. Testing may include collecting data on
the paths users take to do tasks, the errors they make, when and where
they are confused or frustrated, how fast they do a task, whether they
succeed in doing the task, and how satisfied they are with the experience.
The goal of most usability testing is to uncover any problems that users
may encounter so those problems can be fixed.
Links to Related Articles
Usability
Engineering for the Web, Keith Instone, World Wide Web Journal,
http://www.w3j.com/5/s3.instone.html
Usability
Glossary, Usability First,
http://www.usabilityfirst.com/glossary/glossary.taf
What
Steps Are Involved in Usability?
Getting Started Planning the Web
Site
The first step is to understand:
- why you are developing
a site
- who should come
to your site
- when and why
those people might come
In answering these
questions, you establish your objectives for the site. The specific
objectives depend, of course, on your organization and your audience.
You should also
think about usability objectives for the site. General usability objectives
are that a site must be:
- easy to learn
- efficient to
use
- easy to remember
on subsequent visits
- satisfying, with
a minimum number of errors as users go through the site
All the usability
objectives are important for most sites, but you may emphasize different
ones for different audiences and situations. For example, in a site
that is aimed at members of the general public who may only visit once
in a while, you should build a site where almost no learning needs to
take place to use it efficiently.
See
also Methods: Planning the Web
Site
Collecting Data from Users
Because the design is to be based on user needs, data must be collected
about those needs and how well an existing Web site (if there is one)
is meeting those needs. There are a variety of ways to collect that
data, including feedback forms and system metrics (log data on an existing
site), and usability testing of the existing site.
See
also Methods:
Collecting Data From Users
Developing prototypes
It is easier for a user to react to an existing example than to theorize
what would work best. Useful results can be obtained by building a prototype
site, with a minimum of text content and no graphics, for a first round
of usability testing. The prototype can then be used to elicit user
comments and observe the prototype's ability to lead the users through
the tasks they need to perform. It can be built on paper or with simple
HTML.
See also
Methods: Developing Prototypes
Collecting, writing, or revising content
Based on what users need, you must put content into the site. As
you consider information that you already have, think about how useful
and understandable it is. Reading from a computer screen is slower than
reading from paper. Most people want to quickly scan information and
read only small sections. If the information you have is in long paragraphs,
consider revising it. Break it into small chunks with many headings.
Cut out unnecessary words. Use lists and tables so people can find information
quickly. Follow these same guidelines when writing new information for
the Web.
See also
Methods: Collecting, Writing, and Revising Content
Conducting usability tests
Usability testing is an iterative process. The goal of usability testing
is to ascertain what will help users accomplish their tasks and what
may impede them. Using the prototype as a starting point, the usability
testers build a set of scenario tasks they will ask users to attempt.
As detailed information about user success is gathered and reported,
the prototype can be modified and additional aspects of that prototype
tested.
Usability testing
can be done inexpensively or more formally, depending on the size and
budget of the site under development. As the testing team becomes more
experienced, testing can be accomplished more quickly.
See
also Methods:
Conducting and Using Usability Tests
Continuing to assess the site after it
is up
When the site has been implemented, it is incumbent on the developers
or the owners of the content to assess its performance by analyzing
reports, usage logs, and other data sources for the site and by continuing
to gather user feedback on usability.
See also Server
Log Analysis
Log
Analysis links at Usable Web
http://www.usableweb.com/topics/000649-0-0.html
For more information
See also Methods for Designing Usable
Web Sites
What
Is a Usability Test Like?
The focus of a usability test
is the user's experience with a site. The site may exist only as a paper
prototype, or it may be a real working prototype or a site that has
already been launched. The earlier you start to have users try out the
site, the faster and easier it will be to develop the site you want.
During a usability test, specialists
working with the designers and developers of the site watch users working
through tasks with the site and gather other feedback. The purpose is
always to see what is working well and what is not working well
with the goal of improving the site. Usability specialists manage the
test, work directly with the users, and take notes; designers, developers,
and others also observe usually from an adjacent room or from
a live video and audio stream and should also take notes.
Usability specialists gather
all the notes, consolidate and analyze them, and together with the designers
and developers consider the problems they saw and how to solve them.
The result of usability testing is a set of recommendations for improving
the site.
Do
I Need a Lab to Do Usability Testing?
No. You can do usability
testing in either a formal or informal setting. In any type of setting,
your methodology can also range from formal to informal.
You can do effective
usability testing in any of these settings:
- a fixed laboratory
having two or three connected rooms outfitted with audio-visual equipment
- a conference
room, or the user's home or work space, with portable recording equipment
- a conference
room, or the user's home or work space, with no recording equipment,
as long as someone is observing the user and taking notes
- remotely, with
the user in a different location, as long as the observer can monitor
what the user is doing, listen to the user thinking aloud, and interact
with the user by computer or telephone during the session
For more on audio-visual
equipment for recording usability test sessions, see the lists of equipment
for both fixed and portable labs in Usability
Labs.
Links to Related Articles
Usability
Labs: Our Take, in User Interface Engineering,
http://world.std.com/~uieweb/labs.htm
How
Many Participants Are Needed for a Usability Test?
It depends. A
typical range is from five to 12 users in each test. If
each user works with you for an hour, that means one or two days of
testing.
You might need only
three people to help you find serious problems, if you:
- are doing paper
prototypes or are in early development
- plan several
rounds of testing throughout development
- have a fairly
homogenous user population
If you have different
potential user groups (for example, physicians, patients, researchers),
try to include representatives of all these groups. If you are likely
to have users with a range of Web or computer experience, try to include
both less experienced and more experienced users. Those considerations
may push the number of people you need from three to six or nine or
12.
If you want to conduct
formal quantitative testing on your products or systems, you'll need
more people to derive statistical results. For diagnostic usability
testing, five users are usually enough to uncover the major problems
in a product.
If you do iterative
(repeated) usability testing over the course of developing the Web site,
many users will participate in testing one or another version of the
emerging site. Thus, while you may have fewer than 10 participants in
each usability test, you may have 15 to 30 people who have tested some
version of the site before it is launched.
For more information on:
Different goals
for usability testing (diagnostic, comparative, verification), see
How formal or informal should
usability testing be?
Deciding which
type of test to conduct paper
prototyping, see Developing
Prototypes
Needing only five
people to find major problems, see Jakob Nielsen, Why
You Only Need To Test With 5 Users, Alertbox, March 19, 2000,
http://www.useit.com/alertbox/20000319.html

How
Much Does It Cost to Do Usability Testing?
Cost depends,
of course, on the size of the site, how much you need to test, how many
different types of users you anticipate having, and how formal you want
the testing to be.
Having a standard
process and reusable materials makes usability testing faster and less
expensive. If you or your recruiting firm develop a database of users,
recruiting becomes less time consuming and, therefore, cheaper.
Consider these elements
in budgeting for usability testing:
- time to plan:
identify issues to focus on in testing, identify types of users to
involve in testing, write a screening questionnaire to recruit users,
write scenarios for users to follow
- cost of recruiting:
time of in-house person or payment to a recruiting firm (often a good
option)
- time of usability
specialist to become familiar with the site and of team to do a dry
run to see how scenarios work with the site
- cost of renting
laboratory space or a portable lab or other videotaping equipment
if you do not have free access and want to record on videotape
- time of team
to observe users (conduct the test)
- cost of paying
participants or gifts for participants
- time to consider
what the team saw and heard, identify problems, recommend solutions
to those problems
- time to discuss
changes with developers, write up memo of findings and recommendations
Remember to budget
for more than one usability test. Building usability into a Web site
(or any product) is an iterative process. You will find it more valuable
to use your budget to do a few small tests throughout development than
to do just one large test at the end. Each small test might include
anywhere from three to 10 users.
If you are not sure
why to do several small tests, see Why Should I Do
Iterative Usability Testing?
If you need to convince
people that usability testing is worth the cost, see:
The evidence we
cite in How Can I Encourage People in My Organization...?
How to calculate
the cost-benefit of usability in How Can I
Show That Usability Engineering Saves Money?
Why
Should I Do Iterative Usability Testing?
A few small
tests are more valuable than one large test at the end.
- The sooner you
find problems, the less expensive it is to fix them.
- Finding and fixing
problems early means less rework. That not only saves money, it reduces
designers' and developers' frustration.
- You can test
branding (Do people realize whose site it is?), navigation (Can people
find what they need?), and organization of the home page before you
have developed all the content or coded the entire site.
- You can test
many design issues with paper prototypes and then test again when
you have a working site. See Developing
Prototypes.
- You can test
one part of the content and learn valuable lessons to apply to other
parts that aren't yet developed.
- Changes are more
likely to get made early in the development process. Cost, time, and
human reluctance usually lead to ignoring problems that are found
if you test only at the end.
- Testing once
isn't enough to be sure you have a usable site. Use iterative testing
to see whether the way you fixed an earlier problem really works for
users.
- You can use iterative
usability testing to show how the benefits of usability engineering
greatly outweigh the costs. See How Can I Show
That Usability Engineering Saves Money?

How
Can I Show That Usability Engineering Saves Money?
You can use
usability testing to show that the benefits of usability engineering
outweigh the costs.
This method was
first published by Clare-Marie Karat of IBM who used it to show a 100-fold
return on investment for a particular software product. In that case,
spending $60,000 on usability engineering throughout development resulted
in savings of $6,000,000 in the first year alone.
The results from
this technique are especially convincing if the same organization pays
both the development costs of the Web site and the salaries of the people
who use the site. But it should also be convincing to organizations
that really care about how problems on their site cost their external
users time, money, and frustration.
The types of problems
that you might find costing time (and therefore money) are misleading
navigational cues, poorly designed pathways, pages that are so dense
they take a long time to use, etc.
Here is how you
can use usability testing to show how benefits outweigh costs:
1. Do a usability
test on an early version of the Web site (or other product)
this could be the old site or one done without involvement of usability
specialists.
- Use actual
users doing relevant tasks.
- Measure time
to complete tasks.
2. Identify and
fix problems. (Improve the entire site not just the test tasks even
though you will be using the test tasks to show the benefits.)
3. Do a usability
test on the new version of the site.
- Have users
who match the demographics of the first set of users do the same
tasks you used in the first test.
- Measure time
to complete the same tasks.
4. Calculate the
improvement in average time to complete each task.
- You can do
the next steps for each task separately, for just one major task,
or for all the tasks together.
5. Multiply the
time saved by the number of people who are likely to do that task
in a given time period (say, each day).
- If users are
likely to do a task several times a day, you can also multiply by
that number.
- If you have
noted the time saved in seconds or minutes, convert it to hours
because you will want to work in hours in the next step.
6. Identify the
average hourly salary of the users who do that task.
7. Convert time
to dollars by multiplying time saved (in hours) by users' salary (per
hour).
8. Find the one-year
savings by multiplying your previous figure by the number of days
in the year that users are likely to do the task.
- If this is
a work task, use the number of days in the organization's working
year.
- You now have
the total annual savings of your usability changes all due
to time saved by fixing the product so users can do tasks more quickly.
9. Compare the
amount saved to the cost of usability activities.
For More Information:
Karat, C.-M. Business
case approach to cost justification. In Cost-Justifying Usability, Edited
by R. G. Bias and D. J. Mayhew, Boston: Academic Press, 1994, 45-70.

How
Can I Encourage People in My Organization to Conduct Usability Engineering
and Testing?
If you're
trying to persuade the people in your organization to use usability
engineering to design your Web site:
- Quote these statistics:
Research
by User Interface Engineering, Inc., shows that people cannot find
the information they seek on a Web site about 60% of the time.
According
to Elizabeth Millard, "The best sites we've found are usable only
42 percent of the time, and none that we have studied are usable
a majority of the time...."
Studies by Forrester Research estimate that approximately 50% of
potential sales are lost from a site as users can't find data and
that 40% of users do not return to a site when their first visit
is a negative experience.
A study by Zona Research found that 62% of Web shoppers have given
up looking for the item they wanted to buy online.
- Let them observe
a usability test or show them video footage. Observation of user behavior
is very persuasive. The user perspective is just about impossible
for Web site production teams and content developers to see without
talking to or observing actual users.
- Remind them that
usability testing doesn't have to be expensive. Big problems in the
design are obvious after just a few user tests. Jakob Neilsen says,
"You sit somebody down in front of the screen and see immediately
if they click on the right button or the wrong one. As soon as you
see three people make the same mistake, you're better off just fixing
it."
Links to Related Sites
Failure
of Corporate Websites, Jakob Nielsen, Alertbox, http://www.useit.com/alertbox/981018.html
Usability as Barrier
to Entry, Jakob Nielsen, Alertbox, http://www.useit.com/alertbox/991128.html
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