Usability Techniques Lecture 13

Methods There are a variety of approaches to usability evaluation that you may choose to take. The methodologies can be divided into two broad categories: those that gather data from actual users and those that can be applied without actual users present. Your choice of method depends on: Cost of evaluation Appropriateness to project Time constraints Cost of implementation Cost of training new users

Risk Usability evaluations can be conducted at many stages during and after the design and development process. In choosing a method, it is important to calculate the cost not only in terms of time and materials involved, but also in terms of the impact on the end-users, especially considering the cost of losing return visitors to your website due to unusable design.

Cognitive Walkthrough Method Cognitive walkthroughs are performed at any stage of design using a prototype, a conceptual design document, or the final product. This is a more specific version of a design walkthrough, focusing on cognitive principles. Based on a user's goals, a group of evaluators steps through tasks, evaluating at each step how difficult it is for the user to identify and operate the interface element most relevant to their current subgoal and how clearly the system provides feedback to that action. Cognitive walkthroughs take into consideration the user's thought processes that contribute to decision making, such as memory load and ability to reason.

Focus Groups This is a data collecting technique where about 6 to 9 users are brought together to discuss issues relating to the system. A human factors engineer plays the role of a moderator, who needs to prepare the list of issues to be discussed beforehand and seek to gather the needed information from the discussion. This can capture spontaneous user reactions and ideas that evolve in the dynamic group process. Focus groups are also good at discovering how the system being tested differs from the user's current expectations. As we see it, focus groups provide two major benefits. First, they are less expensive than conducting interviews with the same number of people. Second, they rely on group interaction to trigger memories that may not come up during interviews.

Prototyping Prototyping techniques involve developing representations of a target system for evaluation and testing purposes. Prototyping is an essential element of an iterative design approach, where designs are created, evaluated, and refined with the results of testing at each cycle feeding into the design focus of the next cycle. Prototypes can range from extremely simple sketches (low-fidelity prototypes) to full systems that contain nearly all the functionality of the final system (high-fidelity prototypes).

Task Analysis Task analysis is a method that evaluates how people actually accomplish things with software. Through observation and interviews with users, an analyst determines a set of goals belonging to the target user. Then, a set of tasks that support these goals is determined. These are prioritized based on criteria such as the importance of the goal to the organization and the frequency of task performance. The highest priority tasks are decomposed into their individual steps. The level of decomposition varies with the budget and type of system evaluated. The analyst then suggests ways to make the task more efficient or suggests new tasks which more effectively support the goals. It is important to recognize that the analysis is done from the perspective of the end-user—not from the point of view of managers or executives who do not necessarily use the system.

Usability Inspection / Heuristic Evaluation A usability inspection is a review of a system based on a set of guidelines. The review is conducted by a group of experts who are deeply familiar with the concepts of usability in design. The experts focus on a list of areas in design that have been shown to be troublesome for users. Usability guidelines are usually derived from studies in human-computer interaction, ergonomics, graphic design, information design, and cognitive psychology. Some areas that get evaluated are the language used in the system, the amount of recall required of the user at each step in a process, and how the system provides feedback to the user. In particular, issues such as clarity, consistency, navigation, and error minimization are analyzed. Once the problems are discovered, the experts make recommendations for resolving these issues.