Technical Report 2001-021

Usability and Design Decisions in Software Development

Inger Boivie

September 2001


Despite the attention that has been paid to usability in the last few years, the world is still full of inadequate software and frustrated users. The aim of this study was to deepen the understanding of how usability matters are handled in software development projects, particularly at the Swedish National Tax Board (Riksskatteverket - RSV) and the Swedish National Board for Social Securities (Riksförsäkringsverket - RFV).

The main focus of the study was usability and interaction design decisions in software development projects, that is, considerations in the software development process that have implications on the usability of the resulting system. Who makes the decisions about the interaction design? When are they made? What are the sources of input and the main constraints? What support regarding usability matters does the decision maker have access to?

The study was conducted by means of a series of semi-structured interviews with eight developers and usability people in the two organisations.

The study shows that there is no simple answer to who makes the interaction design decisions and when they are made. Rather, it is a case of everybody (developers and user representatives) making this kind of decisions, all the time. Many decisions are never made, they just happen as a result of somebody coding a bit, or modelling a bit. The matter of responsibility for the interaction design was unclear, causing frustration. Use cases are the basis of all design, and thus crucial to the usability of the resulting system. But, use cases were reported to be difficult write. They easily turn into "system operations" providing little or no support for interaction design.

One conclusion is that usability requires hands-on activities throughout the project, or it "gets lost", this is particularly important during construction. One way of achieving continuous attention could be to incorporate a usability role in the system development process and give it sufficient status.

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