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Task Analysis

The general term Task Analysis can be applied to a variety of techniques for identifying and understanding the structure, the flow, and the attributes of tasks. Task analysis identifies the actions and cognitive processes required for a user to complete a task or achieve a particular goal.

A detailed task analysis can be conducted to understand the current system and the information flows within it. These information flows are important to the maintenance of the existing system and must be incorporated or substituted in any new system. Task analysis makes it possible to design and allocate tasks appropriately within the new system. The functions to be included within the system and the user interface can then be accurately specified.

Some of the outputs of a task analysis include:

  • A detailed description of physical, perceptual, and cognitive activities involved with each task
  • Task duration and variability
  • Task frequency
  • Task sequence
  • Task allocation
  • Task complexity
  • Environmental conditions
  • Data and information dependencies
  • Tools required for the task
  • User skills, education, and training

Cognitive task analysis and Hierarchical task analysis are commonly used task analysis techniques. Examples of other task analysis techniques are: Conceptual Task Analysis, GOMS, Timeline Analysis, Tabular Task Analysis, Operator Action Event Trees (OAET), Critical Action and Decision Evaluation Technique (CADET) and LINK Analysis.

Related Links

Web Resources

A detailed description of how to carry out task analysis
Describes task identification and description, information requirements and organizing task analysis data.
A comparison of hierarchical and cognitive task analysis.
  • Joann T. Hackos, Janice C. Redish (1998). User and Task Analysis for Interface Design, John Wiley & Sons, Inc.
This book serves as a practical guide for designing great user interfaces based on studying users, their tasks, their environment and their end goals.
  • Kirwan, B. & Ainsworth, L. K. (1992). A Guide to Task Analysis, London: Taylor and Francis. A text book that contains various task analysis techniques and their use in the systems engineering process.

Authoritative References

  • Hackos, J. & Redish, J. (1998). User and Task Analysis for Interface Design. Chichester: Wiley.
  • Task Analysis - Explained in simple terms
  • Task-based audience segmentation article by Indi Young of Adaptive Path "Task-based segmentation is a technique that defines your target audience by the tasks they perform to achieve a goal. My client didn't need to segment 35,000 employees by the exact role they played, where they were located, their computer aptitude, their career goals, etc. She could classify them instead into four audience segments based on what they were trying to accomplish regarding all aspects of their relationship with the Human Resources department."

Resources from UPA

  • Landesman, Lori. 2001 UPA Conference Paper. Do You Know What Your Users Do? New Techniques in Task Design
  • McQuaid, Heather & Bishop, David. 2001 UPA Conference Paper. An Integrated Method for Evaluating Interfaces
  • Mirel, Barbara. 2001 UPA Conference Paper. Usability for Dynamic Work: Interface Strategies that Make or Break Support for Complex Problem Solving
  • Finstad, Kraig. Taskflow Charting: An Interactive Validation Method for Task Analysis. UPA 2004 Conference.
  • Mclnerney,Paul. Task Analysis Tune-up. UPA 2004 Conference.
  • Parush, Avi. Expanding Our Toolkit: From Descriptive Techniques to In-Depth Analyses. UPA 2005 Conference.
  • Quaet-Faslem, Philipp.; Regn, Judith. User Interface Design for Interventional X-Ray Systems. UPA 2007 Conference.
  • UPA. Ethnographic Awakenings that Changed Techniques and Designs: Three Case Studies. UPA 2006 Conference.

Related Subjects

Cognitive ergonomics - Cognitive Ergonomics could be said to analyze any purposeful human task. Nevertheless, Cognitive Ergonomics (CE henceforth) mainly focuses on work activities having:

  • an emphasized cognitive component (e.g. calculation, decision making, safety-critical environments)
  • operating in a complex, changing environment (i.e. tasks cannot be predetermined)

Detailed description

What can you learn from a task analysis?

According to JoAnn Hackos and Janice (Ginny) Redish, authors of User and Task Analysis for Interface Design, user and task analysis focuses on understanding:

  • what users' goals are; what they are trying to achieve
  • what users actually do to achieve those goals
  • what personal, social, and cultural characteristics the users bring to the tasks
  • how users are influenced by their physical environment
  • how users' previous knowledge and experience influence how they think about their work and the workflow they follow to perform their tasks

Benefits, Advantages and Disadvantages

Benefits

A task analysis allows you to:

  • discover what tasks your web site/app must support
  • determine the appropriate scope of content for your interface
  • decide what applications your interface should include
  • refine or redefine the navigation or search for your website/app to better support users' goalsóto make sure the site is efficient, effective, and satisfying to users
  • build specific Web pages and Web applications that match users' goals, tasks, and steps
  • ensure later on that the design supports all the tasks required

Disadvantages

Be aware that task analysis can be a very time consuming activity if used with a high degree of detail on complex problems. It is possible to get caught in what is loosely termed "analysis paralysis" where more and more detail is investigated. -The USERfit guide

Appropriate Uses

Provides knowledge of the tasks that the user wishes to perform. Thus it is a reference against which the value of the system functions and features can be tested. It is used mainly to investigate an existing situation. It is used to analyze the underlying rationale and purpose of what people are doing, what are they trying to achieve, why are they trying to achieve it, and how are they doing the same. It covers techniques for investigating cognitive processes and physical actions, at a high level of abstraction and in minute detail.

How To

Assembling the data

The data for the Task analysis can be assembled from several places including business requirements, user research, existing competitive products and brainstorming.

Procedure

Task decomposition

The aim of "high level task decomposition" is to decompose the high level tasks and break them down into their constituent subtasks and operations. This 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)

The process of task decomposition is best represented as a structure chart (similar to that used in Hierarchical task analysis). This shows the sequencing of activities by ordering them from left to right. In order to break down a task, the question should be asked "how is this task done?". If a sub-task is identified at a lower level, it is possible to build up the structure by asking "why is this done?". The task decomposition 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.

Task flow diagrams

Task flow analysis will document the details of specific tasks. It can include details of interactions between the user and the current system, or other individuals, and any problems related to them. Copies of screens from the current system may also be taken to provide details of interactive tasks. Task flows will not only show the specific details of current work processes but may also highlight areas where task processes are poorly understood, are carried out differently by different staff, or are inconsistent with the higher level task structure.

Variations

If the tasks are already well understood, it may be sufficient to just identify and document the tasks as part of context of use analysis.

According to Dan Saffer the task analysis can consist in a raw list of features that the final application will have to carry. (Saffer, Designing for Interaction: Creating Smart Applications and Clever Devices , 2006)

Examples of tasks broken down

Brushing teeth

  • Pick up the tooth brush
  • Wet the brush
  • Take the cap off the tube
  • Put paste on the brush
  • Brush the outside of the bottom row of teeth
  • Brush the outside of the top row of teeth
  • Brush the biting surface of the top row of teeth
  • Brush the biting surface of the bottom row of teeth
  • Try to make yourself understood while answering the question of someone outside the door
  • Brush the inside surface of the bottom row of teeth
  • Brush the inside surface of the top row of teeth
  • Spit
  • Rinse the brush
  • Replace the brush in the holder
  • Grasp cup
  • Fill cup with water
  • Rinse teeth with water
  • Spit
  • Replace cup in holder
  • Wipe mouth on sleeve
  • Screw cap back on tube

Borrow book from library

  • go to the library
  • find the required book
  • access library catalog
  • access the search screen
  • enter search criteria
  • identify required book
  • note location
  • go to correct shelf and retrieve book
  • take book to checkout counter

Tools

TaskArchitect is a tool that supports Hierarchical Task Analysis.

Facts

Lifecycle: Process/task analysis
Sources and contributors: 
Nigel Bevan (incorporating material from UsabilityNet), Sudhindra V., Carla Saraiva
Released: 2012-04
© 2010 Usability Professionals Association