Information Technology Reference
In-Depth Information
Table 11.1 Areas where TA
can be applied, adapted from
Kirwan and Ainsworth ( 1992 )
1. Person specification
2. Staffing and job organization
3. Skills and knowledge acquisition
4. Allocation of function
5. Performance assurance
6. Task and interface design
11.2 The Uses of Task Analysis
TA can be used for many different purposes. Kirwan and Ainsworth ( 1992 ), for
example,
identify
six
areas
where
TA
can
be
applied,
which
are
noted in
Table 11.1 .
It should be noted that these areas are not all independent and sometimes
overlap. Here we focus our discussions on the last three items, because these are
the ones that are most closely associated with the process of designing user-
centered systems.
11.2.1 Allocation of Function
The traditional way of allocating functions to users has been to use a Fitts' ( 1951 )
list approach, based on whether the associated tasks are better carried out by
people or by computers. In the original formulation there was often only one
person, and one machine to think about. Nowadays, however, there may be several
people, working together as a team, and several computer-based systems to con-
sider. A task analysis helps you identify the knowledge that is needed to carry out
the functions, and so can be used to inform how the functions are allocated. At the
highest level it also lets you lay out a list of all the tasks that will need to be
allocated. As part of Cognitive Work Analysis, Vicente ( 1999 ) has developed an
approach to take large descriptions of tasks and use the complete set of tasks
across a team of users to allocate sets of tasks to users that make sense to the users
based on the large set rather than traditional job descriptions or existing interfaces.
11.2.2 Performance Assurance
The way that systems are used often changes over time. This is due partly to the
way the system evolves, partly to the way people learn to use the system over time,
and partly to changes in the context in which the system is deployed. The net effect
is that there will often be a change in the tasks that the user carries out. It is
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