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Insights from Human Factors International
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In This Issue Bob Bailey reviews:
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Efficiency in Design
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Bob Bailey, Ph.D., Chief Scientist for HFI, asks the question: How can
designers use existing, readily available, Web-based research to be more
efficient when designing Web sites?
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The Pragmatic Ergonomist
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Dr. Eric Schaffer, Ph.D., CPE, founder and CEO of HFI offers practical
advice.
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It is the nature of most engineering activities that designers never
have enough time to truly perfect their products. Engineers are continuously
confronted with the real-world constraints of tight schedules and limited
resources. Designing Web sites is no exception.
Most Web site designers would like to develop sites that could be easily
used by anyone who attempted to access their site. This is hardly ever
possible. In the end, designers must wisely use the limited resources
available to them to design Web sites that will accommodate the most users
with the least amount of design and testing effort. The following example
uses only four variables (out of many) to show how designers can effectively
limit their many options. The data used in the example were recently reported
by www.thecounter.com/stats/.
In each case the goal was to include enough options to handle at least
90% of users. To accommodate the largest number of users with the least
investment of time and other resources, restrict design decisions to the
following:
- Design primarily for a 16-bit color depth (55%), but also accommodate
color depths of
- 24-bit and 32-bit (38%), and
- 8-bit (5%).
These color depths are used on 98% of all computers.
Even focusing only on these four variables, designers would need to conduct
108 separate tests to determine how the interfaces will perform with the
different combinations. For example:
- Test 1 - Win 98 and Internet Explorer 5 and 800x600 resolution and
16-bit color
- Test 2 - Win 98 and Internet Explorer 4 and 800x600 resolution and
16-bit color
- Test 3 - Win 98 and Netscape 4 and 800x600 resolution and 16-bit color
- Test 4 - Win 95 and Internet Explorer 5 and 800x600 resolution and
16-bit color
- Test 5 - Win 95 and Internet Explorer 4 and 800x600 resolution and
16-bit color
- Test 6 - Win 95 and Netscape 4 and 800x600 resolution and 16-bit color
etc.
In other words, unless there is a very good reason to do so, do not waste
time designing for and conducting usability tests on:
- The Macintosh, WebTV, Linux, Unix operating systems, or any Windows
operating system prior to Win 95,
- Any browser except recent versions of Internet Explorer and Netscape,
- Monitors that have resolutions less than 640x480 or greater than 1280x1024,
and
- Monitors having less than 8-bit color.
As designers, we must clearly understand our intended user population,
design specifically for them, and learn to systematically give up trying
to accommodate all users. Our design time
is finite and our resources are limited. We cannot design a usable website
for everybody! Good designers make good decisions about what not to do.
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Bob points out how many different technical variations there are in Web
design. Indeed, it is impossible to test all their interactions. But most
of these variations can be handled by understanding the range of technologies
and checking the design in different resolutions and browsers. The tough
news is that the USER community has far greater variation then the technical
infrastructure. Users vary on functional requirements, taskflow, skills,
knowledge, motivation, and environment. Now think of the interactions
for that!!!
Luckily there are also a set of understandings and general principles
that we can apply to handle the range of users. These let us accommodate
a wide range of users based on human psychophysics. THEN, there is a methodology
that custom fits the interface to the target user/taskflow/environment.
Without these research-based principles and methodologies your design
has a negligible chance of full success. Just think of the number of interactions!
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Past Issues
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