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1.8 Understanding one research project in the context of related research 17

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In contrast to the example in the sidebar, other research topics in HCI still
have no clear answer, with multiple studies that yield conflicting findings. For
instance, what is the minimum number of people required for usability testing?
See Chapter 10, where the debate still rages on, as there is no agreed answer. The
commonly repeated number is that 5 users is sufficient (although the research re-
ally doesn't say this), and more recent studies have suggested 10 ± 2 users (Hwang
and Salvendy, 2010) or even more than 10 users (Schmettow, 2012). We suggest
that readers turn to Chapter 10 to continue this debate. There may also be some
research questions to which the answers change over time. For instance, in the late
1990s, web users tended to find download speed to be one of the biggest frustra-
tions (Lightner et al., 1996; Pitkow and Kehoe, 1996). User habits and prefer-
ences are fluid and there may be changes over, say, a 20-year period (factors such
as increased availability of broadband Internet access may also play a role). The
biggest frustration for web users right now would most likely be viruses or spam.
When the web first became popular in the mid-1990s, web-wide subject lists and
in-site navigation were popular methods for finding items; now, search boxes are
far more popular methods for finding what you want (and it is possible that the
introduction of Google played a role). When it comes to user preferences, there can
be many different influences, and these preferences may change over time. This is
yet another reason why one research project, at one point in time, does not make
a scientific fact.
You should never get disappointed or upset when you find out that another research
team is working on a similar research question. You should get excited, because it
means that both research teams are moving closer to the end goal of some definitive
scientific answers. The chances are very high that your research method won't be ex-
actly the same, your research questions won't be exactly the same, and your human
participants won't be exactly the same. The fact that other research teams are interested