USER INTERFACE DESIGN UPDATE - December, 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 offers research-based observations -- a year-end list of
design "Dos and Don'ts" that all have recent research to support them.


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


Every year since 1983, I have reviewed and summarized much of
the usability-related research literature that was published during the
previous year. This has provided the basis for the popular, annual
3-day User Interface Update course. My annual two-month "read
and outline" activity provides me with a number of research-based
insights into "what works" and "what does not work" in usability.
I have listed many of these insights in this article. What makes these
"Do's and Don'ts" unique is that they all have recent research to
support them.


General Observations
  1. Do evaluate the goodness of a Web site by evaluating content,
      navigation, visual design, functionality and interactivity, but
      realize that these elements are not totally independent
      (i.e., Web site evaluators have a difficult time separating them
      from each other).
  2. Do make Web sites appear more credible by:
      - Making it easy to distinguish ads from content,
      - Providing quick responses to customer's service questions,
      - Listing the organizations physical address,
      - Having an organization that is well respected outside of the
         Internet,
      - Updating the site frequently with new content,
      - Allowing users to search past content, and
      - Providing a professional looking Web site.
  3. Do use Flash to enhance interfaces knowing that 98% of
      browsers are capable of playing Flash without downloading.
  4. Do design Web application (Weblications) interfaces
      different than traditional Web site interfaces.
  5. Do use "parallel design" concepts when designing user
      interfaces, because participants:
      - Can reach a consensus quickly,
      - Will consider numerous different design alternatives, and
      - Respond to good ideas even when they are contained in
         poor designs.


Display Issues
  6. Do use good headlines when designing newspaper, newsletter
      and other information-based sites because eye tracking
      studies show that users tend to look first at text, not images
      (a margin of nearly two to one favoring text).
  7. Do consider the size of textual information to be used as
      entry points, because
      - When text and images are of similar size, text is more likely
         to be an entry point,
      - Images must be much larger than text to act as an entry
         point, and
      - Larger text dominates over smaller text (normal sized text
         rarely acts as an entry point - even if bold or a hyperlink).
  8. Do put the most important prose text and bullet item information
      toward the top left of a page, because users tend to scan from
      left to right, and top to bottom when reading, but do not follow
      the same pattern between images, titles or links.
  9. Do use common and contiguous background colors to help
      guide users in finding information on a page.
10. Do put the most important information on a Web page at the
      middle-top of the page because that text:
      - Will be seen first, and
      - Text at the bottom of a page is rarely seen.
11. Do use right and left panels for links, because users will
      investigate areas outside the center area:
      - When searching for a specific link, and
      - When visiting a Web site after the first time.
12. Do not use fonts on Web pages that are less than 10 points.
13. Do use 12-point fonts (size=3) on Web pages to elicit
      optimal reading speed for most adults.
14. Do use any of the most common font styles (e.g., Arial,
      Verdana, Georgia, Times New Roman), either serif or sans
      serif fonts, to elicit the fastest possible reading speed.
15. Do use sans serif fonts (e.g., Arial, Verdana) to satisfy user
      preferences.
16. Do use 14-point fonts for older users.


Interaction Issues
17. Do carefully consider the task being performed before making
      decisions about the breadth and depth of a Web site, because
      sites with numerous levels may not degrade performance.
18. Do carefully consider the task being performed before making
      decisions about using or not using frames, because some uses
      of frames will degrade performance.
19. Do not consider users' judgments about "ease of use" as
      accurately representing the speed with which a task can be
      performed.
20. Do use similar item justification and scroll bar orientation to
      produce reliably faster selection times, fewer errors and
      improved preferences in the use of list boxes (and possibly
      Web site scrollbars).
21. Do consider the experience level of users and "frequency of
      use" when selecting widgets in Web sites, particularly when
      deciding between using entry fields and dropdown lists
      (experienced users are faster with entry fields).
22. Do place commonly selected objects close to the edge of a
      window to expedite their selection.
23. Do not be concerned that frequent keyboard use will cause
      carpal tunnel syndrome.


Web Site Design Issues
24. Do design Web sites primarily for use with the Microsoft's
      Windows operating system, unless different (more specific)
      information about the operating systems being used by the
      target audience is available.
25. Do design Web sites primarily to be displayed by the
      Internet Explorer and Netscape browsers.
26. Do design Web sites to work best with screen resolutions
      of the majority of typical users, which worldwide is now
      800x600 pixel resolution.
27. Do design Web sites for use on monitors that show at
      least 256 colors.
28. Do design pages to load in a few seconds; however, keep
      in mind that some users will rate the download speed of slow
      pages as "fast" if they are able to successfully accomplish
      what they intend to do.
29. Do design a Web site that encourages either linking or
      searching behaviors by users.
30. Do design a search capability so that most users will complete
      a successful search on their first attempt.
31. Do design to encourage users to access links (not search) if it
      is important for users to continue to browse the Web site after
      locating their primary target, because:
      - About 60% will continue to browse the site (only 20% of
         "searchers" continued to browse)
      - "Linkers" are three times more likely to find related (valuable)
         content
      - "Linkers" who started with links on the homepage looked at
         almost 10 times more content pages
32. Do design Web sites to have a "moderate amount" of white
      space, because:
      - Users prefer a moderate amount of white space, and
      - There is no reliable performance differences with differing
         amounts of white space.
33. Do design Web sites using a "Fluid" layout, because:
      - Users believed that the "Fluid" layout was best for reading
         and for finding information, and
      - There were no reliable performance differences among the
         methods (left justified, centered or fluid).
34. Do design Web sites with embedded links, because:
      - Users preferred having them embedded, and
      - There were no reliable performance differences between
         embedded links and those outside the text.
35. Do design Web sites with links that are both embedded and
      outside the text on the left margin, because redundant links
      were preferred by users.
36. Do design Web sites with the links in a frame on the left margin,
      because users preferred the frames rather than having the links
      scroll off the page.
37. Do design Web sites that enable textual chat (Instant Messaging)
      between users and Web site assistants.
38. Do design Web sites so that if users must be placed in a queue:
      - They can be continually updated, and
      - The updates can include sounds (so that users can work on
         other things).
39. Do write prose text in Web sites at appropriate reading levels
      for the target audience as calculated using a commonly used
      readability formula, because:
      - The average reading level in North America is at the eighth-
         to ninth-grade,
      - About one in five adults read at the fifth-grade level and
         below, and
      - Adults tend to read at least one or two grade levels below
         their last school grade completed.
40. Do use Rapid Serial Visual Presentation (RSVP) for presenting
      information to users who need to read prose text from small
      displays (PDAs, cell phones, wrist watches), because:
      - RSVP enables an acceptable level of reading performance, and
      - There is no performance or preference differences among
         10-line, 3-line and RSVP.
41. Do use 20-point text presented at speeds of about 250 wpm
      on RSVP-based displays.


Usability Testing
42. Do design "low word count" Web sites (average of 65 words)
      using fewer words, smaller page sizes, fewer graphics, faster
      download times and more font variations (particularly between
      header and body text).
43. Do design "medium word count" Web sites (average of 230
      words) using less body text, organized better into clusters
      (lists and shaded table areas), using lower percent graphics, and
      with more colors to help distinguish headers.
44. Do design "high word count" Web sites (average of 800 words)
      using less body text, organized well into clusters (lists and shaded
      table areas), with more text links, large page size, lower percent
      graphics, and using more colors to help distinguish headers.
45. Do use eye-tracking methods to determine confusion rates
      from users in usability testing.
46. Do require usability testing clients to make specific and focused
      requests, including usability objectives, specific definitions of
      success and clear time limits for task completion.
47. Do plan on inadvertently creating new usability problems when
      fixing problems identified by previous usability testing.
48. Do plan on finding and fixing about 37% of the problems in a
      system with each performance test (i.e., each iteration), which
      means that to detect and correct 95% of the usability problems
      it would take
      - At least six tests, and
      - 105 participants.
49. Do have members of the design team use a prototype Web
      site to create an estimate of the time it should take an
      experienced user to access information; then use this time
      to set usability objectives (e.g., 85% of the users shall not
      need more than 125% of the expert users' time for each task).
50. Do use a "large" number of users (e.g., over 100) for performance
      tests, because of:
      - The complexity of Web sites
      - Hundreds or thousands of pages
      - Hundreds of features and paths, and
      - The need to determine the prevalence of problems in target
         populations,
      - Only 35% of problems were identified after testing five users.
51. Do use automated testing methods for some, if not all, of the
      performance testing for a new system, because automated
      testing allows:
      - More rapid data collection and analysis,
      - The use of a large numbers of users, and
      - Quick evaluation of content that keeps changing.
52. Do provide online learning materials that primarily use a
      traditional prose text format, because it elicits better learning
      (however users preferred a hypertext format).
53. Do not use testers or test participants to be involved in a
      test when they have a cold, because:
      - They will respond more slowly,
      - They will detect fewer problems, and
      - They will have reduced energy and motivation levels.


Users
54. Do use the following age categories when designing and
      using study information:
      - Old-old: 75 and older
      - Older: 60-74
      - Middle-aged: 40-59
      - Young: 18-39
55. Do ensure that important system (Web site) sounds are
      louder for older users.
56. Do use TFT screens rather than CRT screens to elicit the
      fastest possible reading performance from users
      (older users benefit even more than younger users).


Note: the references for these do's and don'ts are posted at
http://www.humanfactors.com/library/dec02.asp
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The Ergonomic Pragmatist
Eric Schaffer, Ph.D., CPE, Founder and CEO of HFI


Great list Bob.  But let me share a few ideas and concerns.


1. I agree that 98% of browsers can show flash without a download.
But without usability training 98% of developers will use flash in
ways that makes the site worse.


2. Web applications are different. But for most cases do NOT try
to mimic a windows applications. Users will expect to be in a
browser and have the back button work.


3. Give it up Bob.  It is too late to move the scroll bar to the left.


4. Be careful about making decisions just because the users said
they preferred it. There may be hidden performance costs (as in #35
where redundant links will take space that could be used for useful
content). Also, one of my favorite quotes of the year... "Because
someone likes something doesn't mean it will move merchandise."
Carolyn Burke - Sr. eCommerce Manager at Royal Bank


5. Obviously testing with 5 users was a bad idea.  But 100s will be
impractical for all but remote summative tests (which are much less
valuable then formative tests early in the design process). Be
practical and run formative tests with 12-30 subjects.


6. Automated testing does let you run lots of users in remote
locations. It works well for summative testing. But for formative testing
I recommend in person studies where you can watch users, notice
their reactions, and talk freely about the design.
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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 2003 seminars can be downloaded at
http://www.humanfactors.com/downloads/2003calendar.pdf
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Suggestions, comments, questions?
HFI editors at mailto:hfi@humanfactors.com.


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