Hierarchical Task Analysis


Chung P, Zhang J, Johnson T, et al. An extended hierarchical task analysis for error prediction in medical devices. AMIA Annu Symp Proc 2003:165.


A hierarchical task analysis (HTA) describes an activity in terms of its specific goals, subgoals, operations, and plans. Once the analysis is complete, the task activity is described in detail.


To construct an in-depth list of goals or tasks associated with a specific process.

How do I use this tool?

1. DEFINE TASK BEING ANALYZED, as well as the purpose of the task analysis.

2. CONDUCT DATA COLLECTION. Pay particular attention to areas such as technology, machine and team member interaction, decisionmaking, and task constraints to better understand the process.

3. DETERMINE THE OVERALL GOAL OF THE TASK. This should be in place at the top of the task hierarchy.

4. DETERMINE TASK SUB-GOALS. Decompose the overall goal into corresponding subgoals. Together, these subgoals should comprise the tasks necessary to accomplish the overall goal.

5. PERFORM SUB-GOAL DECOMPOSITION. Subgoals should be futher broken down into additional subgoals and operations. Continue this process until you reach an appropriate operation, which specifies the action that actually needs to be done to accomplish the goal. There should always be an operation at the bottom level of any branch within an HTA.

6. DEVELOP PLANS ANALYSIS. After describing all subgoals and operations, add the plans. Plans explain how a goal should be accomplished. These may be in the format "do A, then, do B, then do C", or "do A, or do B and do C".

Expertise Required
Users of this tool usually have some training or experience in its use.

Provides significant insight into the task being analyzed.

Creates an output that is useful for several other human factors analysis methods and tools.

Supplies a comprehensive task description.

Is useful across nearly any domain.


Typically not directly useful for determining design solutions.

Primarily descriptive instead of analytical.

Intricate or sizeable tasks can cause an HTA to be time and labor intensive.

Where can I go to learn more?

Stanton N, Salmon P, Walker G, et al. Task analysis methods. Human factors methods: a practical guide for engineering and design. Great Britain: Ashgate; 2005. p. 45-76.