We investigated the importance of the social context for people's voluntary contributions to a national park in Costa Rica, using a natural field experiment. Some subjects make actual contributions while others state their hypothetical contribution. Both the degree of anonymity and information provided about the contributions of others influence subject contributions in the hypothesized direction. We found a substantial hypothetical bias with regard to the amount contributed. However, the influence of the social contexts is about the same when the subjects make actual monetary contributions as when they state their hypothetical contributions. Our results have important implications for validity testing of stated preference methods: a comparison between hypothetical and actual behavior should be done for a given social context.

This is an appreciation of the life and work of Michael Jones-Lee. It describes his pioneering role in establishing and developing the theory and practice of the elicitation of monetary values for changes in risks to life, health and safety, using stated preference methods.

Environmental valuation is the branch of environmental economics in which researchers estimate the economic value of environmental goods and services. Environmental valuation has been practiced for decades. However, there are some ideas in the field of environmental valuation held by many environmental economists and nonenvironmental economists that appear to be outdated. This article discusses three such ideas: 1) that it is better to estimate willingness-to-pay values than willingness-to-accept values; 2) that stated preference valuation methods are questionable because they are based on hypothetical choices rather than real choices; and 3) that it is better to use a repeated-choice question format than a single-choice format in choiceexperiments. We discuss the origins of each idea and why the idea became prevalent in the first place. We then review recent literature, which casts doubt on the idea. We conclude with a reminder for researchers—in environmental economics and in other economic fields—to periodically reassess ideas they currently hold in light of recent research developments and in light of the context in which they are used.