Asymmetric dominance effects in choice experiments and contingent valuation

While a dominated choice involves a situation in which one option clearly dominates another on all relevant dimensions, an asymmetrically dominated choice typically involves more than two options in which at least two options do not dominate each other but one (but not both) of those options does dominate a third option. We demonstrate that the introduction of an asymmetrically dominated option can significantly impact upon choices between non-dominated options within the same choice set. Furthermore, we show that this effect can then translate into significant impacts upon subsequent valuations for those non-dominated options. Such findings are at odds with standard theory yet accord with a substantial number of findings within the marketing and experimental economics literatures. More fundamentally these results show that the introduction of alternatives which are, from a formal perspective, irrelevant can significantly impact upon non-market valuation estimates derived from both choice experiments and contingent valuation studies. We consider the impact of such effects and their implications for future valuation research.