Estimations in scrum/agile environments often gets tangled in conversations about how big of an effort that is required. The questions that are often asked are “how much of effort?”, “how long/sprints it will take?”, “Is it too complex?”
Scrum provides a model where these questions are easily compressed to a simple thing called story points. Story points is a number denoting the complexity/effort/time taken by the team to solve a problem (story). Story points are often a number of Fibonacci series. (1, 2, 3, 5, 8, 13 …). The scrum team defines what it means by a 1 pointer story. For example one of our teams defined a 1 pointer as “one line of code change”. Also as the number of unknowns in a story is high, team provide higher story points for the story.
However the size of the story points is not important because
- Story point size is specific to the team and can not be used to compare teams. A story could be sized differently by different teams based on the understanding of the product, technology and experience.
- When a management provides a commitment on a given epic/release to the customer, the delivery timeline is often determined by the velocity and not by individual story sizes.
- Story points are a relative sizing of the stories and not a exact reflection of complexity/effort
- Bigger story points does not mean higher customer value. A refactoring story or a story of lower business impact could be sized bigger.
- Story points are time bound. The team could size the story differently depending on their understanding, as their knowledge/understanding changes their story sizes also change. This is one of the reasons some teams re-look at the story sizes during sprint planning although they are sized.
Please let us know your thoughts, using story points? does size matter?