This type of metric allows for overall progress in decarbonising the energy sector to be tracked over time. However, the larger the scale of assessment (and the longer the time horizon for assessment), the more difficult and uncertain it becomes to attribute an outcome or impact to a specific intervention. When coupled with ex-post evaluation and later compared to the intended objectives of a project, such information can form a useful evidence base for evaluating effectiveness. Unlike mitigation, the ultimate impacts of specific interventions (e.g. increased adaptive capacity and resilience) are difficult to model ex-ante or measure directly.