When evaluating the impact of a biodiversity conservation intervention, a 'counterfactual' is needed, as true experimental controls are typically unavailable. Counterfactuals are possible alternative system trajectories in the absence of an intervention and comparing observed outcomes against the chosen counterfactual allows the impact (change attributable to the intervention) to be determined. Since counterfactuals are hypothetical scenarios, and by definition never occur, they must be estimated. Sometimes there may be many plausible counterfactuals, given that they can include multiple drivers of biodiversity change, and be defined on a range of spatial or temporal scales. Here we posit that, by definition, conservation interventions always take place in social-ecological systems (SES; ecological systems integrated with human actors). Evaluating the impact of an intervention within an SES therefore means taking into account the counterfactuals assumed by different human actors. Use of different counterfactuals by different actors will give rise to perceived differences in the impacts of interventions, which may lead to disagreement about its success or the effectiveness of the underlying approach. Despite that there are biophysical biodiversity trends, it is often true that no single counterfactual is definitively the 'right one' for conservation assessment, so multiple evaluations of intervention efficacy could be considered justifiable. Therefore, we propose the need to calculate a quantity termed the sum of perceived differences, which captures the range of impact estimates associated with different actors within a given SES. The sum of perceived differences gives some indication how closely actors within an SES agree on the impacts of an intervention. We illustrate the concept of perceived differences using a set of global, national and regional case studies. We discuss options for minimising the sum, drawing upon literatures from conservation science, psychology, behavioural economics, management and finance. Article impact statement: Sum of perceived differences captures impact range in social-ecological systems, indicating how closely actors agree on intervention impacts. This article is protected by copyright. All rights reserved.

中文翻译：

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在评估生物多样性保护对社会生态系统的影响时协调多个反事实

在评估生物多样性保护干预的影响时，需要“反事实”，因为通常无法获得真正的实验控制。在没有干预的情况下，反事实是可能的替代系统轨迹，将观察到的结果与所选的反事实进行比较，可以确定影响（归因于干预的变化）。由于反事实是假设的场景，并且根据定义从未发生过，因此必须对其进行估计。有时可能会有许多看似合理的反事实，因为它们可以包括生物多样性变化的多种驱动因素，并在一系列空间或时间尺度上进行定义。在这里，我们假设，根据定义，保护干预总是发生在社会生态系统（SES；与人类行为者相结合的生态系统）中。因此，评估 SES 内干预的影响意味着考虑不同人类行为者假设的反事实。不同行为者使用不同的反事实会导致干预影响的感知差异，这可能导致对其成功或基本方法的有效性产生分歧。尽管存在生物物理生物多样性趋势，但通常情况下，没有一个反事实绝对是保护评估的“正确”，因此可以认为对干预效果的多重评估是合理的。因此，我们建议需要计算一个称为感知差异总和的数量，它捕获与给定 SES 内不同参与者相关的影响估计范围。感知差异的总和表明了 SES 内的参与者对干预影响的一致程度。我们使用一组全球、国家和区域案例研究来说明感知差异的概念。我们利用保护科学、心理学、行为经济学、管理和金融方面的文献，讨论了最小化总和的选项。文章影响陈述：感知差异的总和反映了社会生态系统中的影响范围，表明参与者对干预影响的一致程度。本文受版权保护。版权所有。我们利用保护科学、心理学、行为经济学、管理和金融方面的文献，讨论了最小化总和的选项。文章影响陈述：感知差异的总和反映了社会生态系统中的影响范围，表明参与者对干预影响的一致程度。本文受版权保护。版权所有。我们利用保护科学、心理学、行为经济学、管理和金融方面的文献，讨论了最小化总和的选项。文章影响陈述：感知差异的总和反映了社会生态系统中的影响范围，表明参与者对干预影响的一致程度。本文受版权保护。版权所有。