Reducing protest responses by deliberative monetary valuation: Improving the validity of biodiversity valuation

This paper focuses on examining the validity of biodiversity valuation methodologies. The results of a group deliberation technique (deliberative monetary valuation) are compared to those derived from a contingent valuation (CV) survey using the same environmental topic. Evidence is here presented that DMV can address some of the limitations of CV; namely a prevalence for lexicographic preference ordering due to psychological reasons and the lack of a priori or well-formed preferences. Both of these methodological shortcomings can result in protest responses which decrease the external validity of results. It is common environmental valuation methodology practice to exclude protest responses from the analysis on the grounds that they are illegitimate choices, thus the sample and consequently the environmental valuation analysis may become less representative of the population. An advantage of the DMV methodology is that it was found to significantly reduce the rate of protest responses to less than half (from 29% to 13%). Furthermore, DMV significantly increased the proportion of positive bids but not the amounts contributed. In relation to preference formation issues, we suggest rethinking the current practice of the DMV method, and propose dedicating the entire initial discussion session to introducing the good outside of a valuation context.