ゼロリスクの結果の価値に関する研究 An Examination of Zero-risk Effect in Willingness to Pay for Protective Actions

Even when the amount of loss reduction is exactly the same, a protective action that leaves no loss may be valued more than others that leave some. It is called "zero-risk effect, " which was examined in this study. One hundred and forty-four undergraduates rated their willingness to pay (WTP) for three protective actions that would leave 800, 400, or 0 deaths. Results showed that the WTP difference between actions resulting in 400 deaths and no death was larger than that between actions resulting in 800 deaths and 400 deaths. The effect was shown not only in a negative framing condition, but also in a positive one. The results thus established the robustness of zero-risk effect, which cannot be explained in terms of the negative framing effect. Finally, implications for risk management and risk communication were discussed.