I came across this wonderful short post entitled “User Stories: Value and Size”. The most interesting paragraph for me is this one:
Maximizing work not done is the art of our trade. The business value of a story is looked into precisely for this reason. If you don’t have a good reason business value) behind a given piece of functionality (story), you are wasting time by working on it.
Brilliant. I can’t add more but this few words: If you are building products maybe finding the Business Value for a User Story is hard, really hard. But if you can’t find one, you loose credibility of the team. The team will have the feeling that you are making up the value of the feature. So talk with customers, talk with them a lot, talk with many of them in order to find how much the story is worth with respect the total price they will pay for each copy, and then project the revenue this story will have, given how much copies you are going to realistically sell. That will be just an estimate, but a very educated one.