Reading: Jackson pp 564-590

decision-tree approach to test design. Most questions about perception of flavors or products will fall into three categories. First, people want to know, "Are these two products different?" This calls for the overall difference test, also referred to as a discrimination test. These tests usually take the form of a forced-choice procedure, where participants are asked to select one choice from among a set of products in which only one is physically different from some standard sample. The second common question is, "How are they different?" In other words, the goal is to specify, in perceptual terms, how products differ, in what qualities have they changed and to what extent. This set of procedures is referred to as descriptive analysis. In its most common form, a group of trained individuals examines the products and provides numerical ratings for the perceive intensity of each attribute. This provides quantitative sensory specification of each product that may be compared statistically. The third common question concerns consumer likes and dislikes. These tests are generally conducted with untrained persons who are usually users or purchasers of the product. They are asked to provide quantitative ratings describing the strength of their liking or disliking for the product as a whole, and may also be probed about their opinion regarding specific characteristics. Alternatively, they may simply be asked to pick which product they like best from a set of alternatives.