June 2010 Edition
Computer Science Department, University of Cape Town
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In previous units you have focused on design (units 2, 3 & 6) and on users (units 4, 5 & 7). But of course users and computers do not exist in isolation: apart from some games applications, computers are there to support users in going about their every-day work. To be useful, computer systems have to help users to do the things they need to do. To be usable, they need to help the users do them in a way that seems natural to those users. Task analysis is concerned with understanding how users go about their work at the moment, so that new computer systems can be designed to help with that work rather than hindering it or forcing it into a different pattern.
In this unit, we will study three different approaches to analysing users' tasks:
Hierarchical Task Analysis (HTA) involves describing users' tasks in terms of the activities involved at different levels of detail. Superficially, it looks a bit like the GOMS analysis that you studied in unit 7 but, as you will see later in this unit, it is concerned with larger-scale tasks in the work domain, rather than user tasks (involving the details of thinking and acting with a particular device).
Knowledge-Based (KB) Analysis involves creating taxonomies of objects that are important within the work domain.
Entity-Relationship (ER) Modelling involves describing the entities (objects and actors) involved in the domain and relationships between those entities. You may have come across this type of approach before, if you have studied systems analysis, but don't worry if you haven't.
In this unit, we will cover how to create each of these types of representation of a task and how to use that representation to reason about design. We will focus most on HTA.