This metric may help describe the WHO dimension of impact, which details which stakeholders the investment or enterprise aims to reach with the outcome. This metric may also help clarify how underserved they were prior to the investment. For more on the alignment of IRIS metrics to the five dimensions of impact, see IRIS+ and the Five Dimensions of Impact (https://iris.thegiin.org/document/iris-and-the-five-dimensions/). No single metric is sufficient to understand an impact; rather, metrics are selected as a set across all dimensions of impact. When possible, the selection of metrics to measure and describe the five dimensions should be based on best practice and evidence.