What is task analysis?

Task analysis is an observation-based technique that elicits knowledge from the users for whom a product is intended. First, the researchers have to familiarize themselves with the product domain so that they can converse knowledgeably with these users. After this initial period of discovery, they interview actual and/or target users of the product for 2 - 3 hours apiece. All users are asked some scripted questions, but the interviews have a relatively unstructured format. The lack of a sequential format helps ensure that the users' normal task flow is reflected rather than the researchers' preconceptions. Some of the crucial information that task analysis aims to uncover (at a minimum): who the different groups of users are and how they differ which tasks are performed by each specific group of users which tasks they must perform which tasks they perform frequently how they currently perform each important or frequent task what sequence they perform these tasks in which measures of user performance (accuracy, speed, etc.) are relevant

The Handbook of Human-Computer Interaction (ed. Martin Helander) notes that task analysis can be used to "identify user-system interface design features which are compatible with system requirements and human capabilities." Task analysis is a valuable tool for defining product requirements and for specifying design constraints. Getting these boundaries established early in the design process will ensure that prototypes focus on solving the right problems using the right interaction techniques.

What can I apply it to?

Any product for which (a) goal-oriented tasks can be identified; (b) criteria for improvement in user performance can be formulated; and (c) users can be observed and consulted. As this implies, task analysis has a wide range of applications, from call centers to online shopping to nuclear plant control. However, task analysis is always most useful for a transactional system - that is, a system which performs an operation based on a user input. If a product's main purpose is informational (like an encyclopedia or a reference website), the sequence of tasks and the interaction techniques for user input of data are less critical.

How much does it cost?

The amount of time required for a task analysis depends upon the number of different types of users, the number of tasks each type of user performs with the product, and the complexity of those tasks. The more users we interview, the more complete a representation we get of how the system is used. Realistically, a point of diminishing returns is reached where additional interviews provide mostly a confirmation of the previous interviews. Deciding when that point of diminishing returns has arrived is a practical matter depending upon the customer's financial constraints and knowledge requirements. For this reason, we bill task analysis at an hourly rate, allowing the client to stop whenever their goals are reached.

What do I get?

A final report that details our findings and makes recommendations about how the product's sequential organization and interaction techniques can be improved.

Where does it fit into the design process?

At the very beginning, as part of requirements' gathering; and in the middle, after the information architecture is defined and before prototyping begins. Task analysis is often performed in the process of designing a user interface specification.