Impact Evaluation of Forest Conservation Programs: Benefit-Cost Analysis, Without the Economics

Economists are increasingly using impact evaluation methods to measure the effectiveness of forest conservation programs. Theoretical analysis of two complementary economic models demonstrates that the average treatment effect on the treated (ATT) typically reported by these studies can be related to an economic measure of program performance only under very restrictive conditions. This is because the ATT is usually expressed in purely physical terms (e.g., avoided deforestation) and ignores heterogeneity in the costs and benefits of conservation programs. For the same reasons, clinical trials are a misleading analogy for the evaluation of conservation programs. To be more useful for economic analyses of conservation programs, impact evaluations should work toward developing measures of program outcomes that are economically more relevant, data that would enable the evaluation of impacts on forest degradation (not just deforestation) and primary forests (not forests in general), better estimates of spatially disaggregated treatment effects (not program-wide averages), and better information on the accuracy of estimated treatment effects as predictors of future risks.