Task analysis

Draft

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Introduction

According to Task Analysis (retrieved 16:26, 26 April 2011 (CEST)) “Task analysis involves learning about your users' goals, what they want to do on your Web site and how they work. It can also mean learning about specific task users must do to meet those goals and what steps they take to accomplish those tasks. A task analysis complements a user analysis. [...] Tasks analysis allows you to discover what tasks your Web site must support and to determine the appropriate content scope. It also helps you to decide what applications your Web site should include. It can assist you in refining or re-defining the navigation or search to better support users' goals or to build pages and applications that match users' goals, tasks, and steps.”. Usability.net provides a similar definition.

According to NASA's Usability toolkit, retrieved 16:26, 26 April 2011 (CEST),

Task analysis defines what a user is required to do in terms of actions and/or cognitive processes to achieve a task. A detailed task analysis can be conducted to understand a system and the information flow within it. These information flows are important to the maintenance of the system. Failure to allocate sufficient resources to this activity increases the potential for costly problems arising in later phases of development. Task analysis makes it possible to design and allocate tasks appropriately within the new system. Once the tasks are defined, the functionality required to support the tasks can be accurately specified.

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Method

According to Usability.net, retrieved 16:26, 26 April 2011 (CEST), a typical task analysis consists first in breaking down a high-level task “into constituent subtasks and operations. his will show an overall structure of the main user tasks. At a lower level it may be desirable to show the task flows, decision processes and even screen layouts (see task flow analysis, below)”. Such a task decompositions can be carried out using the following stages:

1. Identify the task to be analysed.
2. Break this down into between 4 and 8 subtasks. These subtasks should be specified in terms of objectives and, between them, should cover the whole area of interest.
3. Draw the subtasks as a layered diagram ensuring that it is complete.
4. Decide upon the level of detail into which to decompose. Making a conscious decision at this stage will ensure that all the subtask decompositions are treated consistently. It may be decided that the decomposition should continue until flows are more easily represented as a task flow diagram.
5. . Continue the decomposition process, ensuring that the decompositions and numbering are consistent. It is usually helpful to produce a written account as well as the decomposition diagram.
6. Present the analysis to someone else who has not been involved in the decomposition but who knows the tasks well enough to check for consistency.

(Usabilitynet.org

Once tasks are analyzed they also can be represetned as task flow diagrams.

Software

• TaskArchitect is a (hierarchical) task analysis tool. A free version allows to define 20 tasks and 10 properties. Standard and Pro versions are $400, $1250.

Links

Short introductions

• Task Analysis

• Task analysis by J. Nielsen at Usability.net

Web sites or links pages

• Task analysis at Dey Alexander Consulting.

Bibliography

• Crandall, B., Klein, G., Hoffman, R. R. (2006). Working Minds: A Practitioner's Guide to Cognitive Task Analysis. MIT Press, ISBN 9780262532815.