Explain the HTA method. Hierarchical task analysis (HTA) is the most popular task analysis method and it involves describing activities under analysis in terms of hierarchy of goals, sub-goals, plans, and operations. It is a practical process in which an analyst collects a range of information about a task and its context in order to arrive at a satisfactory outcome where potential problems have been identified and where potential solutions have been proffered. Through a hierarchy of goals, HTA explores tasks by specifying the tasks a person is supposed to do and plans specifying the conditions when to perform subordinate goals. The HTA begins with the statement of overall goal followed by statements of the subordinate operations, and the plans to achieve the goal. The subordinate plans and operations are then checked for adequacy of re-description of the goal into subordinations and plans. The outcome is an in-depth description of task activities.
In HTA, tasks are represented in form of hierarchies of goals and sub-goals, using the idea of plans to show when sub-goals need to be carried out. Therefore, the HTA process involves decomposition of tasks into subtasks and the process is repeated until they reach a level of elementary tasks. Each and every subtask or operation is identified by its goal, the measures required to achieve the goal, the circumstances under which the goal becomes significant or “active,” and the criteria that marks the goal achievement. In task analysis, it is always important to think of the reason why the task is carried out. Thus a task has a purpose or goal criteria against which the task can be judged to be satisfactory or otherwise.
Task analysis helps the analyst in understanding and representing the system and human performances in a particular task or situation. The analysis process involves identifying tasks, collecting task data, analyzing the data so that each task is understood, and then producing a documented representation of the analyzed tasks. The relation between the super ordinate task and a set of subtasks is that they are both governed by plans expressed as, for example, assortment rules, procedures, or time-sharing principles.
The main aim of HTA is to give sufficient details when describing tasks, with the required level of resolution depending on the specific reasons for the analysis (for instance, training requirements, interaction design, risk analysis, interface design, and so on). HTA can be looked at as an organized way of investigating how tasks are organized and how they adapt to be used in a different purposes and contexts within the field of human factors.