Click here to purchase the entire book in PDF format. Testing for stimulus attributes Up to now, we have been assuming that you already know what you're looking for. For example, you're asking subjects to rate loudness, or coffee sweetness, or codec quality. However, there will be times when you don't know what you're looking for. Two people bring in two different cups of coffee and you want to find out what the difference is. You can assume that the difference is ``sweetness'' and ask your subjects to rate this, but if it turns out that the actual difference is ``temperature'' then your test wasn't very helpful. Consequently, there are a number of different test methodologies that are used for finding out what the differences between stimuli are, so that you can come back later and rate those differences. The big two in use by most people are called Repertory Grid Technique and Descriptive Analysis. In both of these cases, the goal is to find out what words best describe the attributes that make your stimuli different. For both types of tests, let's use the example of coffee. There are four different coffee shops in your neighbourhood, A, B, C, and D. You want to find out what makes their coffee different from each other, and how different those attributes are... Let's use the two techniques to find this information...