An impact map is a visualisation of scope and underlying assumptions, created collaboratively by senior technical and business people. It is a mind-map grown during a discussion facilitated by considering the following four aspects:
Project plans and requirements documents are often shopping lists of features, without any context why such things are important. Without a clear mapping of deliverables to business objectives, and a justification of that mapping through impacts that need to be supported, it is incredibly difficult to argue why certain items should or shouldn’t be invested in. In larger organisations with many project stakeholders or product sponsors, this leads to huge scope-creep as everyone’s pet features and ideas are bundled in.
An impact map puts all the deliverables in the context of the impacts that they are supposed to support. This allows us to compare deliverables and avoid over-investing in less important areas of a system. It also helps to throw out deliverables that do not really contribute to any impact that is critical for a particular goal. Finally, by connecting deliverables to impacts and goals, an impact map shows the chain of reasoning that led to a feature suggestion. This allows us to scrutinise those decisions better and re-evaluate them as new information becomes available through delivery.