Decision-support systems often include a strategy for selecting tests in their field of application. This strategy in essence captures procedural knowledge and serves to provide support for the reasoning processes involved. Generally, a test-selection strategy is offered in which tests are selected sequentially. For our field of application, we noticed that such a strategy would be an oversimplification, and decided to acquire knowledge about the actual strategy used by the experts. To this end, we composed a method that comprised an unstructured interview to gain general insight in the test-selection strategy used, and a subsequent structured interview, simulating daily practice through vignettes, to acquire full details. We used the method with two experts in our field of application and found that it closely fitted in with their daily practice and resulted in a large amount of detailed knowledge.