He Wumeng, Nabangchang Orapan, Erdman Krista, Vanko Alex C A, Poudel Prapti, Giri Chandra, Vincent Jeffrey R
Economics and Management School, Wuhan University, Wuhan, Hubei China.
School of Economics, Sukhothai Thammathirat Open University, Pakkret Nonthaburi, Thailand.
Environ Resour Econ (Dordr). 2023;84(3):845-876. doi: 10.1007/s10640-021-00644-z. Epub 2022 Feb 6.
Economists typically estimate the average treatment effect on the treated (ATT) when evaluating government programs. The economic interpretation of the ATT can be ambiguous when program outcomes are measured in purely physical terms, as they often are in evaluations of environmental programs (e.g., avoided deforestation). This paper presents an approach for inferring economic impacts from physical outcomes when the ATT is estimated using propensity-score matching. For the case of forest protection, we show that a protection program's ex post economic impact, as perceived by the government agency responsible for protection decisions, can be proxied by a weighted ATT, with the weights derived from the propensity of being treated (i.e., protected). We apply this new metric to mangrove protection in Thailand during 1987-2000. We find that the government's protection program avoided the loss of 12.8% of the economic value associated with the protected mangrove area. This estimate is about a quarter smaller than the conventional ATT for avoided deforestation, 17.3 percentage points. The difference between the two measures indicates that the program tended to be less effective at reducing deforestation in locations where the government perceived the net benefits of protection as being greater, which is the opposite of the relationship that would characterize a maximally effective program.
经济学家在评估政府项目时通常会估计处理组的平均处理效应（ATT）。当项目成果以纯粹的实物指标衡量时，ATT的经济解释可能会含糊不清，环境项目评估（如避免森林砍伐）往往就是如此。本文提出了一种方法，用于在使用倾向得分匹配估计ATT时，从实物成果推断经济影响。对于森林保护的情况，我们表明，负责保护决策的政府机构所认为的保护项目的事后经济影响，可以用加权ATT来代理，权重来自接受处理（即受到保护）的倾向。我们将这一新指标应用于1987 - 2000年泰国的红树林保护。我们发现，政府的保护项目避免了与受保护红树林面积相关的12.8%的经济价值损失。这一估计比避免森林砍伐的传统ATT小约四分之一，即17.3个百分点。这两种衡量方法之间的差异表明，在政府认为保护净效益更大的地区，该项目在减少森林砍伐方面往往效果较差，这与一个最有效项目应有的关系相反。
