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Bailey, R.W., Koyani, S.J. and Nall, J. (2000), Usability testing of
several health information Websites, National Cancer
Institute Technical Report, September.
Kangas, S. (2001), Layout
and content of popular sites
Kellener, E., Barnes, G.M. and Lingard, R. (2001), Effects of scroll
bar orientation and item justification, Proceedings
of the Human Factors and Ergonomics Society 45th Annual Meeting
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Are scrollbars located close enough to where users typically work with
a Website or list box to encourage the fastest possible use?
Studies at the National Cancer Institute (NCI) have shown that many users
preferred to have the Website content index located in the right
panel because it was closer to the traditional right-placed scrollbar
(Bailey, Koyani and Nall, 2000). Kangas (2001) reported that about 51%
of the most popular Websites are located flush against the left margin
of the browser, with the index on the left site as well. The remaining
sites are centered on the page. None were found with the Website aligned
to the right margin of the browser. Obviously, the scrollbar remains in
its traditional location near the right margin.
Erik Kellener, Michael Barnes and Robert Lingard at California State
University in Northridge, California recently reported a study that provides
some insights into this issue.
They noted that in most list boxes the alphanumeric information tended
to be left-justified, while the scroll bar was always placed on the right
side of the box. Like with the Websites, the text was on the left, and
the scrollbar was on the right. Advocates of the scrollbar remaining on
the right side argued that these controls
have been on the right side "from the beginning." This was most
likely done, they say, to accommodate a "right-handed" user
population. The few advocates of placing the scrollbar on the left
side, justified their opinions by observing that the scrollbar should
be as close as possible to the left-justified text. It is very interesting
that they could find no research studies on this topic.
They conducted a study where they had a group of right-handed subjects
make numerous selections from list boxes. Users had to scroll to the correct
answer and then make the selection. Half of the items (text) were left-justified
and the other half (numbers) were right-justified. Half the scrollbars
were placed on the traditional right side, the other half on the left
side of the list boxes. They found that subjects were reliably faster
with, and preferred, similar item justification and scrollbar orientation
– that is, right justification with scrollbars on the right, and
left justification with scrollbars on the left. There was no appreciable
difference between right and left.
They conducted a second study, with different participants to try to
replicate the first study, using only text items (e.g., the names of states,
provinces and territories). Again, they found that similar item justification
and scroll bar orientation produced reliably faster selection times.
It is not surprising that users will perform better with scrollbars that
are located as close to the items being selected as possible. This is
probably true for all vertical scrollbars, both in list boxes and in the
Website itself. As designers our choice is simple, we can either move
the most frequently used information to be near the scrollbar, or move
the scrollbar to be closer to the information. Roller buttons on the mouse
have helped to alleviate, but not eliminate, this problem.
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