The survey designed to analyse consumer perceptions was divided into three parts. In the first part, subjects were asked
questions about the frequency with which they consume shellfish, the shellfish species they most commonly consume, how much they spend on these products, and the primary characteristics they take into account when making decisions as consumers (either at home or in a restaurant). The second part aimed to investigate the perceived meaning of quality and the importance of food safety as an attribute that affects quality. This section also intended to determine the level of awareness regarding the health risks associated with consuming certain products and subjects’ reaction in response to this information. It includes questions about common sources of information on food safety issues and what products and phases are subject to increased risk. And the survey's third part was designed to estimate the economic value, to potential
consumers, of improvements in aquaculture product food safety guarantees that would result from applying an additional inspection and guarantee program. This economic assessment yields information on confidence in extant monitoring levels and on how marine pollution–related problems affect the value that consumers assign to products from a given region. The methods used for this assessment of stated preferences are based (like those in [26]) on the following assumption: the most that a consumer is willing to pay for improvements—in this case, an additional guarantee for environmental quality (Hicksian consumer surplus or compensating variation)—is equivalent to the value of the utility or welfare whose loss gives rise to the need for a guarantee. In this study, this is the loss in the value of the product due to marine
pollution and the willingness to pay is defined as the amount that must be taken away from the person's income while keeping his utility constant. Formally, it is measured as the following compensation
value: