“Time is Money” : Using Contingent Labor and Money Contributions to Value a National Park

The inclusion of non-monetary payments may be appropriate in developing countries. In this paper, we depart from this previous literature by adopting a non-excluding approach between two payment alternatives, which we claim is appropriate in urban, middle-or high-income settings. We adopt two elicitation questions, monetary and labor contributions, to estimate the economic value of a conservation project for a unique peri-urban national park. Estimates show that providing a scenario where there are only time contributions or only money contributions may underestimate the total value of the environmental good. We also show that previous theoretically inconsistent applications might overestimate the willingness to pay. We conclude that, in addition to using an endogenous estimation of the opportunity cost of time, researchers need a theoretically consistent framework in which individuals’ contributions of both time and money can obtain estimates of the total willingness to pay