The main goals of the chapter are to accomplish the following:
Describe different kinds of requirements.
Allow you to identify different kinds of requirements from a simple description.
Explain additional data gathering techniques and how they may be used to discover requirements.
Enable you to develop a persona and a scenario from a simple description.
Describe use cases as a way to capture interaction in detail.
Discovering requirements focuses on exploring the problem space and defining what will be developed. In the case of interaction design, this includes: understanding the target users and their capabilities; how a new product might support users in their daily lives; users’ current tasks, goals, and contexts; constraints on the product’s performance; and so on. This understanding forms the basis of the product’s requirements and underpins design and construction.
It may seem artificial to distinguish between requirements, design, and evaluation activities because they are so closely related, especially in an iterative development cycle like the one used for interaction design. In practice, they are all intertwined, with some design taking place while requirements are being discovered and the design evolving through a series of evaluation—redesign cycles. With short, iterative development cycles, it’s easy to confuse the purpose of different activities. However, each of them has a different emphasis and specific goals, and each of them is necessary to produce a quality product.
This chapter describes the requirements activity in more detail, and it introduces some techniques specifically used to explore the problem space, define what to build, and characterize the target audience.