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From: Human Factors International <hfi@humanfactors.com> 
Subject: UI Design Update Newsletter - March, 2002 

USER INTERFACE DESIGN UPDATE - March, 2002

Insights from Human Factors International, Inc. (HFI)
Providing consulting and training in software ergonomics.
(http://www.humanfactors.com/)

Every month HFI reviews the most useful developments in
UI research from major conferences and publications.
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In this issue:

Dr. Bob Bailey -- Challenging current practice.

The Ergonomic Pragmatist, Dr. Eric Schaffer, gives practical advice.
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Bob Bailey, Ph.D., Chief Scientist for HFI

Is it better to have more items on a page and requiring fewer pages
to be accessed (wide breadth), or to have fewer items per page
and require more pages to be accessed (more depth)? Based
primarily on studies reported three years ago by Larson and
Czerwinski (1998) and Zaphiris and Mtei (1998), designers have
been encouraged to construct broad, shallow sites.

Is it better to show one page containing frames with simultaneous
menus, or to use the more traditional sequential strategies? In the
former situation, users stay on the same page and select from
different menus that are located in different frames. There is no
need to change pages. In the latter case, users click from page-to-
page until they reach a target or answer a question. Designers have
been encouraged to use simultaneous menus whenever the task
requires users to continually use the Back button (Hochheiser and
Shneiderman, 2000).

Can users tell when they experience an interface that helps or
hinders performance? Many designers still ask users whether or
not the interface is adequately designed.

A recent study from Japan (Tsunoda, et.al., 2001) challenges
some of our previous conclusions. Based on their review of the
literature, they proposed three hypotheses:

 - H1: No matter what users are doing, fewer layers will result
   in faster task performance times ("broad" is always better than
   "deep").

 - H2: No matter what users are doing, task performance times
   using simultaneous menus within frames on one page will be
   faster than using the more traditional method of clicking from
   page-to-page.

 - H3: Task performance time and ease of use will be closely
   associated, i.e., when users do well with a task they will
   prefer the interface, and when they do poorly they will dislike
   the interface.

Their first experiment had 89 participants search for information
using five different formats:

 - Four-pages showing 3 items on each page for a total of 12
    items, and requiring users to make a minimum of 4 clicks,

 - Three-pages showing 9 items on the first page and 3 on the
   other two pages for a total of 15 items, and requiring users
   to make a minimum of 3 clicks,

 - Two-pages showing 27 items on the first page and 3 on the
   other page for a total of 30 items, and requiring users to
   make a minimum of 2 clicks,

 - One-page showing all 81 items and requiring users to make
   only 1 click, and

 - One-page with three frames showing 9 items on the first
   frame and 2 items in each of the other frames for a total of
   15 items, and requiring users to make a minimum of 3 clicks
   (no new pages are selected).

They found no reliable difference in task performance times
across the four "page" conditions, but did report that the frame
condition took reliably longer than all of the "page" conditions.
The "Four-page" and "Three-page" layouts were preferred.

In their second experiment they kept the breadth and depth
the same, but added "price" to the final page or frame. Also,
they changed the task to one of finding either the best or worst
price. This required users to move back and forth between
pages (or frames) to compare the prices of products before
making an answer. By changing the task they also changed the
minimum number clicks that were required:

 - The Four-page format required users to make a minimum of
   22 clicks (not 4),

 - The Three-page format required users to make a minimum
   of 15 clicks (not 3),

 - The Two-page format required users to make a minimum of
   8 clicks (not 2),

 - The One-page format required the same 1 click as before, and

 - The One-page with three frames required users to make a
   minimum of 9 clicks (not 3).

In this experiment, the Four-page and the Three-page layouts
produced reliably slower task performance. The "One-page" and
"One-page with frames" were reliably preferred over the other three
formats.

None of their hypotheses were true. Having fewer layers did not
guarantee faster task performance times, and using simultaneous
menus within frames did not guarantee better performance times.
Finally, users preferred some formats that did not help their
performance, and disliked others that helped. This study reminds
us (again) to use caution when applying research results in actual
situations. Using research-based guidelines can help direct the
initial decisions, but then these decisions should be validated with
appropriate usability testing.
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The Ergonomic Pragmatist
Eric Schaffer, Ph.D., CPE, Founder and CEO of HFI

Well Bob... I am worried you are starting to scare people. Like
EVERY field, ergonomics has a constant churn of theory and
research at its cutting edge. There is always new controversy and
new insights. But there is certainly a core of solid research-based
understanding that we should rely on... and it is at least usually right.

We must be careful in generalizing research findings. Even after
spending time with you on it, I still don't really understand the frame
design the Japanese study tested.

Probably the most important insight of the month is that usable
design is NOT just common sense. We need to apply the
established principles and add new insights as they are validated.
We must also always test our designs, as the field is complicated.
No one gets it right the first time.
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3-day Annual User Interface Update Seminar presented by
Dr. Robert Bailey.
http://www.humanfactors.com/training/annualupdate.asp.
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REGISTER for Bob's UI Update Seminar:

The schedule for 2002 seminars can be downloaded at
http://www.humanfactors.com/downloads/2002calendar.pdf
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Suggestions, comments, questions?
HFI editors at mailto:hfi@humanfactors.com.

Want past issues?
http://www.humanfactors.com/library/pastissues.asp

Subscribe? - http://www.humanfactors.com/library/subscribe.asp
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