As mentioned in How many participants?, the tree you’re testing may serve more than one user group. As discussed in Chapter ~, Writing Tasks, there are two basic methods to testing multiple types of users:

• Running a separate test for each user group.
  Each test has its own set of tasks aimed at that specific user group. Your recruiting challenge is to point the right participants to the right test.
  
  
• Running a single test  with multiple user groups.
  The test has a set of tasks that can be reasonably performed by all user groups. Your recruiting challenge is to identify (after the results are in) which user group each participant belongs to.
  
  
  

If you’re running a separate test for each user group, the test design is simple – you have your tree and a list of tasks that are aimed at that user group.

To recruit for this test, you would typically identify qualified participants first, then point them to the study. In other words, the qualifying step would be done before they start the test. For more on this, see ~“Screening for specific participants” later in this chapter.

If you’re targeting several user groups with the same test, you first need to make sure that each user group can reasonably perform the tasks you’ve set. For more on this, see Chapter ~, Writing Tasks.

Because they’re all doing the same test, you need a way to identify each participant’s user group. This is usually done by adding a survey question to the test. Later, when you’re analyzing the results, you can filter them by this question to compare between the user groups.

Here’s a typical survey question that identifies the participant’s user group:

• ss

Note that, like any survey question, it should:

• Provide clear and mutually exclusive choices
  
  
• Include an “Other” option
  
  
• Be written in the user’s language, which may be different from the organization's terminology
  
  

Sometimes, it may not be possible for a single question to determine the user group. If your testing tool lets you filter results based on combinations of survey questions, you can use 2 (or even 3) questions to determine the user group:

• ss

For more on how to filter results by user group, see Chapter ~, Analyzing Results.

Next: Using web ads