Used in a laboratory or survey setting, the declarative methods are very widely used to estimate the consumers preferences. The experimental economic incentive methods allows to make up for hypothetical bias which can affect purely declarative methods. This work sets out several experiments based on methodological comparisons allowing to test the inter-methods validity and to begin external measure validity question. In line with literature previous works, this work allows to highlight assets and limits of the non-hypothetical measures (BDM mechanism and real choice experiment), first one relative to another, second relative to hedonic measures. Two major results were obtained. First, the BDM mechanism allows to reveal the preferences of a product even if its unit value is low. Secondly, both methods used to reveal willingness to pay give coherent results regarding aggregate level, but different regarding individual level, without being able to impute these differences to methods or to instability of the participants behaviour. Finally, this work argues and illustrates assets of field situation measures which would allow to increase predictive values of the willingness to pay measures.
