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180 CHAPTER 7 Case studies

7.11 INFORMAL CASE STUDIES

Although careful planning and design are never completely inappropriate in HCI
research, there may be times when the construction of a fully fledged case study is
overkill. You may be starting a completely new project, without any understanding of
the application domain or the needs of the users. Or, you might be interested in get-
ting some initial response to a proposed design for a new feature that you've designed
for a software tool. Yet another possibility involves validation: can you collect some
data to document the success of your completed design?
In situations like these, your goal is not to develop a general model or to construct
a rigorous argument. Rather, you are more interested in feedback that will help you
understand a new situation or a “sanity check” that will indicate whether a new idea
is worth pursuing. Informal case studies with a small number (as few as one) of care-
fully chosen participants can be very valuable sources of feedback. Informal case
studies are frequently used by HCI researchers to describe the successful use of a
tool—see the Interfaces for people with quadriplegia sidebar for an example.
These case studies are “informal” in the sense that some of the guidelines and pro-
cedures might be relaxed in favor of expediency. As you're not looking to make broad,
generally applicable claims, you do not need the rigorous planning and record-keeping
that is necessary to establish chains of evidence. You might forego a theoretical back-
ground or defined analytical framework in favor of simple note-taking and observation.
Imagine a foray into designing a tool for an unfamiliar domain. You might con-
sider running a fully fledged case study, asking several experts in the domain what
they do, how they do it, and what they might want in a tool. The potential utility of
this study might be significant, but you might need some initial background to plan
the details. An informal case study with one potential user might help you gather
the initial understanding that is necessary for designing the complete case study.
Sometimes, you may find that limits on available resources (time and personnel)
make it impossible for you to conduct a complete study. If this happens, informal
case studies may be your best option for understanding the problem.
If you are looking for feedback on a proposed design or constructed interface,
an informal case study can be an attractive alternative to user studies or observation
sessions. Particularly if you can work with a participant who will use your tool on
a problem that interests him or her, you can use an informal session to document an
instance of the successful use of your tool in the intended domain. A negative result
can be informative here as well: if it turns out that your design is fundamentally
flawed, your single case can help you identify the error early, saving you the trouble
of designing a more thorough summative evaluation.
Even if your case study is informal, your criteria for selecting participants should
not be. Although the lesser time commitments of these shorter studies may make
them more appealing to many participants, the relatively loose and informal nature
may be troublesome to some. You probably don't want to do an informal, preliminary
study of a proposed interface with a critical participant who won't be able to handle a
few glitches along the way. People who have invested in the success of your project