4. Measuring and characterizing perceptions

The aim of this stage is to provide representative measures of perceptual differences between products in the product space, as reported by subjects. The most common test in this context is the semantic scale rating. To do this, you need to define a set of relevant terms to represent the perceived differences between products. A free verbalization session on different products, involving several subjects, either individually or in groups, will help generate these terms, by suggesting the following questions:

• Describe each product in terms that are characteristic from the point of view of your perception.

• Choose the 2 products in the product space that you consider to be very different. What terms characterize their differences from a perceptual point of view? Same question with very similar products....