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170 Chapter 6 The process of interaction design

quality assurance and testing to make sure that the final product is "fit-for-purpose."
Evaluation does not replace these activities, but complements and enhances them.
We devote Chapters 10 through 14 to the important subject of evaluation.
The activities of developing alternative designs, building interactive versions of
the design, and evaluation are intertwined: alternatives are evaluated through the
interactive versions of the designs and the results are fed back into further design.
This iteration is one of the key characteristics of the interaction design process,
which we introduced in Chapter 1.

6.2.2 Three key characteristics of the interaction design process I
There are three characteristics that we believe should form a key part of the interac-
tion design process. These are: a user focus, specific usability criteria, and iteration.
The need to focus on users has been emphasized throughout this book, so you
will not be surprised to see that it forms a central plank of our view on the interac-
tion design process. While a process cannot, in itself, guarantee that a development
will involve users, it can encourage focus on such issues and provide opportunities
for evaluation and user feedback. I
Specific usability and user experience goals should be identified, clearly docu-
mented, and agreed upon at the beginning of the project. They help designers to
choose between different alternative designs and to check on progress as the prod-
uct is developed.
Iteration allows designs to be refined based on feedback. As users and design-
ers engage with the domain and start to discuss requirements, needs, hopes and as-
pirations, then different insights into what is needed, what will help, and what is
feasible will emerge. This leads to a need for iteration, for the activities to inform
each other and to be repeated. However good the designers are and however clear
the users may think their vision is of the required artifact, it will be necessary to re-
vise ideas in light of feedback, several times. This is particularly true if you are try-
ing to innovate. Innovation rarely emerges whole and ready to go. It takes time,
evolution, trial and error, and a great deal of patience. Iteration is inevitable be-
cause designers never get the solution right the first time (Gould and Lewis, 1985).
We shall return to these issues and expand upon them in Chapter 9.

6.3 Some practical issues
Before we consider hbw the activities and key characteristics of interaction design
can be pulled together into a coherent process, we want to consider some questions
highlighted by the discussion so far. These questions must be answered if we are
going to be able to "do" interaction design in practice. These are:

Who are the users?
What do we mea; by needs?
How do you generate alternative designs?
How do you choose among alternatives?