Confusion or conflation in this area can be catastrophic (Scope and Time)
T-shirt sized Swag estimates Groomed and pointed
day, sprint, release
The bull’s-eye analogy The bullseye.. Diagram and speak to this mental model of certainty. The bull’s-eye analogy is wonderful at picturing increasing or decreasing levels of certitude.
Just as it is difficult to predict what a person will accomplish in a given day, it is very difficult to concretely predict what a team will accomplish in a given Sprint and even more difficult to predict what a team will accomplish in a release or a quarter. The bull’s-eye analogy is wonderful at picturing increasing/decreasing levels of certitude.
As the day is easier to predict than the sprint, the sprint is easier to predict than the roadmap. All three are subject to change. They are simply different scales of certitude and we do our best to ensure that the larger loop goals are secured by meeting the smaller loop goals. Another way to picture this is with a target where the outer rings represent lower degrees of certitude while the inner circles represent greater degrees of certainty or accuracy. All of life is like this. It's easier to predict things closer to the present and harder to predict the further you go into the future. In the iterative method, we simply introduce discrete periods of time, namely the day, the sprint, and in this case the roadmap.