Un no como respuesta: interpretación, tratamiento y análisis en estudios de valoración contingente

The Contingent Valuation Method (CVM) is widely used to assist public decisions. It is worrying, however, that a significant proportion of individuals provide a willingness to pay from scratch, which is not reconcilable with the economic theory. Using three CVM exercises carried out in Colombia, this study examines what motivates these non-economic zeros (protest) responses and their implications for the estimation of monetary values. Our results show that protest responses are supported by ethical and fairness motivations, which should be taken into account in decision making but are ignored if one follows the conventional CVM procedure.