Kahneman, D., &Knetsch, J. L. (1992). Valuing public goods: the purchase of moral satisfaction. Journal of environmental economics and management, 22(1), 57-70.
Contingent valuation surveys in which respondents state their willingness to pay (WTP) for public goods are coming into use in cost-benefit analyses and in litigation over environmental losses. The validity of the method is brought into question by several experimental observations. An embedding effect is demonstrated, in which WTP for a good varies depending on whether it is evaluated on its own or as part ...