Large sums of money are invested annually in conservation interventions, but evidence of the conservation impact of these investments is often lacking or conflicting. Just as important, there is much confusion among scientists and practitioners about how the effectiveness of policy interventions should be evaluated. In a new paper led by Vanessa Adams, we show how even robust estimates of ecological impact can fail to estimate the impact of specific policy interventions. The effectiveness of policies depends crucially on human preferences and responses to regulations and incentives that cannot be captured by studies of ecological impact. The paper demonstrates inadequacies in traditional evaluation approaches and calls on researchers to invoke counterfactual thinking, asking the question ‘what would have happened in the absence of the intervention?’ – with the support of rigorous evaluation approaches, and more thoughtful consideration of human dimensions. The paper proposes practical steps that all evaluations can implement now to immediately improve their credibility and accountability.
