TABLE OF CONTENTS The first step in cost-justifying usability engineering on a particular software development project is to lay out a usability engineering plan for that project.
The Usability Engineering Lifecycle (Mayhew, 1999) documents a structured and systematic approach to addressing usability within the product development process. It consists of a set of usability engineering tasks applied in a particular order at specified points in an overall software development lifecycle. Readers familiar with the Usability Engineering Lifecycle might wish to skip this section, which provides an overview of the Lifecycle. Readers interested in more detail than that provided in this overview are referred to Mayhew (1999).
Several types of tasks are included in the Usability Engineering Lifecycle, as follows:
Structured usability requirements analysis tasks
An explicit usability goal setting task, driven directly from requirements analysis data
Tasks supporting a structured, top-down approach to user interface design that is driven directly from usability goals and requirements data
Objective usability evaluation tasks for iterating design towards usability goals
The chart in Figure 3.1 represents, in summary, visual form, the Usability Engineering Lifecycle. The overall Lifecycle is cast in three phases: Requirements Analysis, Design/Testing/Development, and Installation. Specific usability engineering tasks within each phase are presented in boxes, and arrows show the basic order in which tasks should be carried out. Much of the sequencing of tasks is iterative, and the specific places where iterations would most typically occur are illustrated by arrows returning to earlier points in the Lifecycle.
