Describe the Method

This section of the test plan is a detailed description of how you are going to carry out the research with the participants, and how the test session will unfold. Essentially, it is a synopsis of your test design. It should provide an overview of each facet of the test from the time the participants arrive until the time they leave, in enough detail so that someone observing the test will know roughly what to expect. If you are questioning why this amount of detail is necessary in the test plan, the following reasons should satisfy your curiosity.

■ It enables others to understand and visualize what will happen so that they can comment and make suggestions accordingly.
■ It enables you as the test developer to focus on what has to be done and the types of materials that have to be developed before participants arrive.
■ It reveals the need to communicate your plans to additional resources whom you might have forgotten, such as a receptionist who will greet the participants in a corporate lobby when they first arrive,

■ It allows multiple test moderators (if that is required by the test design) to conduct the test in as similar a mariner to each other as possible. Test design is one of the more highly specialized skills required of a usability professional, often requiring knowledge of experimental design and method and basic statistical analysis. Designing a test requires one to clearly iden- tify and understand the test objectives, and then to select the test design that will effectively ferret out the answers to the questions posed. If the test design

is flawed or if the test is carried out with little attention to experimental rigor, then the results will be suspect. Not only can this result in faulty recommendations, but it also sabotages the progress of usability engineering
per se within the organization. Therefore, the first few times that you conduct a usability test, get advice and feedback on your test design from someone more experienced than you.
The test design is mainly predicated upon your test objectives — what you need to learn about the product and its audience. The design will be greatly affected by your resources, your constraints, and your creativity. Constraints are time, money, management backing, development team support, ability to acquire participants, and other real-world concerns. The following sections  give examples of test designs for some of the most common situations you will face. Following that, we present some guidelines for ensuring experimental rigor.
The simplest test design, shown in the table in the next section, consists of testing several different users, all from one type of user group (e.g., older adults), and having them perform a series of representative tasks on different parts of the web site.