À qui se fier : à la publicité ou à des experts au-dessus de tout soupçon ?

Once households start loosing confidence in their economic future, they get increasingly concerned by the net utility of their consumption expenditures. Yet, ex-ante estimation of the value-for-money, that they expect to derive from their purchases and choices, may be a costly exercise ? if only, time-wise ?, which most often they cannot afford. Rather than experimenting by themselves, on their own, by successive trials and errors, they tend to turn to cheaper efficiency indicators of products and services provided by advertisements or more neutral sources, such as experts? reports edited by consumers? unions. Reviewing a very simple case, we unfortunately demonstrate that this second ? allegedly more reliable ? type of information may not be more dependable than the first, mainly because of the complexity of multi-attribute evaluations but perhaps also because of a lack of means to guarantee the representativeness of their quality control measurements. While advertisers are challenged by their competitors and are thus forced to be extremely cautious in rationally justifying their superiority claims 2 , consumers? organizations operate in a monopolistic environment enjoying, like the press because of their status of countervailing power, more degrees of freedom. For these reasons, we recommend that their comparative testing procedures be certified and regularly audited by public authorities ; we also urge them to spontaneously become more methodologically transparent.