Information Technology Reference
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Chapter 11
Methodology I: Task Analysis
Abstract Task analysis (TA) is a useful tool for describing and understanding
how people perform particular tasks. Task analyses can be used for several pur-
poses ranging from describing behavior to helping decide how to allocate tasks to a
team. There are several methods of TA that can be used to describe the user's tasks
at different levels of abstraction. We describe some of the most commonly used
methods and illustrate the use of TA with some example applications of TA. TA is
widely used but when using TA there are considerations to keep in mind such as
the fact that many approaches require an initial interface or specification, and that
many do not include context multiple users or ranges of users. These consider-
ations help describe where and when TA can be successfully applied and where
TA will be extended in the future.
11.1 Introduction
You should by now be familiar with the idea that when we are designing user-
centered systems we are thinking about particular people doing particular tasks in
a particular context. So far in this topic we have looked in some detail at people-
related aspects, and at some of the context-related aspects. In this chapter we focus
more on task-related issues.
To understand what people do when they perform a task we use a technique
called task analysis (TA). TA provides a way to describe the users' tasks and
subtasks, the structure and hierarchy of these tasks, and the knowledge they
already have or need to acquire to perform the tasks. Using these descriptions it
becomes possible to predict how long users will take to learn a task, and how long
they will take to perform a task. In this chapter we will mostly focus on the sorts of
tasks that are nowadays carried out using some form of computer-based system.
TA can be used in most stages of system development. Before carrying out a
TA,
however,
Diaper
(
2004
)
suggests
that
you
first
identify
the
stages
of
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