task analysis

 

Task analysis is the analysis of how a task is accomplished, including a detailed description of both manual and mental activities, task and element durations, task frequency, task allocation, task complexity, environmental conditions, necessary clothing and equipment, and any other unique factors involved in or required for one or more people to perform a given task.

This information can then be used for many purposes, such as personnel selection and training, tool or equipment design, procedure design (e.g., design of checklists or decision support systems) and automation.

The term "task" is often used interchangeably with activity or process. Task analysis is often results in a hierarchical representation of what steps it takes to perform a task for which there is a goal and for which there is some lowest-level "action" that is performed. Task analysis is often performed by human factors professionals.

Task analysis may be of manual tasks, such as bricklaying, and be analyzed as time and motion studies using concepts from industrial engineering. Cognitive task analysis is applied to modern work environments such as supervisory control where little physical works occurs, but the tasks are more related to situation assessment, decision making, and response planning and execution.

Task analysis is also used in education. It is a model that is applied to classroom tasks to discover which curriculum components are well matched to the capabilities of students with learning disabilities and which task modification might be necessary. It discovers which tasks a person hasn't mastered, and the information processing demands of tasks that are easy or problematic. In behavior modification, it is a breakdown of a complex behavioral sequence into steps. This often serves as the basis for Chaining.

Task analysis: data collection

The analyst will often directly observe tasks performed by practitioners (as in ethnographic studies) and may audio-tape and videotape actual task performance. A more controlled study may be done in a laboratory, as in experimental psychology, where the practitioner may work with a simulation of the real task environment. An analysis of actual work procedures, manuals, etc. is also valuable.

Task analysis: representational forms

There are a wide variety of ways to represent tasks. A common method of analysis and resulting diagram is a hierarchical task analysis (HTA), which is a part-whole decomposition of the overall task. A flowchart is another common diagram that results from a task analysis.

GOTA - goal objectives tasks and activities

K Tara Smith in his paper to the Ergonomics Society Conference (1999) outlined an alternative approach for capturing and representing tasks. In essence it starts by defining the states of the overall manned system that are desirable and then maps the tasks that need to occur to bring it back to that state when a particular event occurs.

• An example - air traffic control

• • Desirable manned system state – knowledge of all aircraft in sector

• • • Event - new aircraft entered sector

The tasks are then described as the set of events that need to happen to get back to the desirable manned system state. Although this is an over simple example it illustrates how the approach is structured.

When used in anger the method inevitably captures and represents multiple desirable manned system states and multiple events. Additionally, a task on one task line can trigger an event for another.

The advantages of his method are:

• The desirable manned system state are unlikely to change with the introduction of a new system providing a more stable baseline for analysing current tasks and proposed future ones.
• The method prompts the analyst to cover all tasks ( i.e. until the desirable manned system state is re-established)
• Allows you to specify performance requirements in terms of the percentage time in desirable manned system states.

A variation of this method has been successfully used to assess hazardous tasks within the oil & gas industry.

Computational models of cognitive task performance

A number of computational cognitive modeling frameworks exist that can be used to model more details of generative mechanisms of cognitive performance of tasks. Such frameworks include GOMS, MIDAS, ACT-R, Soar, and EPIC.

Task analysis versus work domain analysis

If task analysis is likened to a set of instructions on how to navigate from point A to point B, then work domain analysis (WDA) is like having a map of the terrain that includes Point A and Point B (see Lintern, 2005). WDA is broader and focuses on the environmental constraints and opportunities for behavior, as in Gibsonian ecological psychology and ecological interface design.

Task analysis and documentation

Since the 1980s, a major change in technical documentation has been to emphasize the tasks performed with a system rather than documenting the system itself. (Hackos and Redish, 1998) In software documentation particularly, long printed technical manuals that exhaustively describe every function of the software are being replaced by online help organized into tasks. This is part of the new emphasis on usability and user-centered design rather than system/software/product design.

According to the historian of technical communication, R. John Brockmann, this task orientation in technical documentation began with publishing guidelines issued by IBM in the late 1980s. Later IBM studies led to John Carroll's theory of minimalism in the 1990s.

With the development of XML as a markup language suitable for both print and online documentation (replacing SGML with its focus on print), IBM developed the Darwin Information Typing Architecture XML standard in 2000. Now an OASIS standard, DITA has a strong emphasis on task analysis. Its three basic information types are Task, Concept, and Reference. Tasks are analyzed into steps, with a main goal of identifying steps that are reusable in multiple tasks.

See also

• Business process mapping and business process modeling
• Cognitive ergonomics
• Job analysis
• Workflow
• Human reliability

Further reading

• Crandall, B., Klein, G., and Hoffman, R. (2006). Working minds: A practitioner's guide to cognitive task analysis. MIT Press. 
• Kirwan, B. and Ainsworth, L. (Eds.) (1992). A guide to task analysis. Taylor and Francis. 
• Hackos, JoAnn T. and Redish, Janice C. (1998). User and Task Analysis for Interface Design. Wiley. 
• Brockmann, R. John (1986). Writing Better Computer User Documentation - From Paper to Online. Wiley-Interscience. 
• Carroll, John M. (1990). The Nurnberg Funnel - Designing Minimalist Instruction for Practical Computer Skill. MIT. 

External links

• Task analysis
• Usability Glossary: Task Analysis
• UsabilityNet: Task analysis methods

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