MAP-01-011 HFI Technical Guide - Human Factors Integration ...

MAP-01-011 – HFI Technical Guide (STGP 11)• As the analyst has control over the TTA categories used, potentially anyaspect of a task can be evaluated. In particular, the technique could beadapted to assess the cognitive components associated with tasks (goals,decisions, SA).• Potentially extremely exhaustive, if the correct categories are used.• Disadvantages• As the TTA is potentially so exhaustive, it is a very time consumingtechnique to apply and analyse. The HTA only serves to add to the highapplication time. Furthermore, obtaining information about the tasks(observation, interview etc) creates even more work for the analyst.• Data regarding the reliability and validity of the technique is not available inthe literature.• A HTA for the task/system under analysis may suffice in most cases.A3.4.3Task DecompositionTask decomposition begins with a task description, such as a HTA describinghow each step of the task under analysis is performed. The analyst then gathersfurther information about specific aspects of each task step (such as time taken,controls used, cues initiating each action etc). The information for each of thetask steps can then be presented using a set of sub-headings. This allows therelevant information for each task step to be decomposed into a series ofstatements regarding the task. The categories used to decompose the tasksteps should be chosen by the analyst based on the requirements of theanalysis. There are numerous decomposition categories that can be used andnew categories can be developed if required by the analysis.It is recommended that the analyst should develop a set of specific categories forthe system under analysis. The task decomposition technique can be used atany stage in the design process, either in the early design stages to provide adetailed task analysis and determine which aspects of the task require furthersystem design inputs or to evaluate existing operational systems or devices.• Advantages• Through choosing which decomposition categories to use, the analyst candetermine the direction of the analysis.• Flexible technique, allowing any factors associated with the task to beassessed.• A task decomposition analysis has the potential to provide a verycomprehensive analysis of a particular task.• The structure of the method ensures that all issues of interest areconsidered and evaluated for each of the task steps.May 2006 Page A3-30 Issue 4