On Measuring Existence Value
质疑存在价值只能通过条件价值评估法测量的共识，认为纯存在价值可能源于简单模型而非人们真实偏好，提出非使用价值也可从行为观察中获取，并建议实证测量方法。
The prevailing consensus that existence value can only be measured by contingent valuation is questioned. The concern is over "pure" existence value, a change in welfare when a public good changes that leaves no trace in behavior. Pure existence value may well be more a consequence of the simple models used to characterize nonuse value than a reflection of how people value public goods. If so, nonuse value can in principle be obtained from observing behavior as well as from asking questions, which offers a prospect for cross-checks and corroboration using both approaches. Some possibilities for empirical measurement are suggested.