Michael de la Maza asks the question what exactly is a Story Point? He went looking for an answer and found many: “Story points represent nebulous units of time.” or “Story point is a random measure used by Scrum teams. This is used to measure the effort required to implement a story.” or “...a story point estimate is an amalgamation of effort involved in developing the feature, the complexity of developing it, the risk inherent in it, and so on.” [Mike Cohn, Agile Estimation and Planning].
Michael goes on to document how they’re used: “Truth be told velocity really is a productivity
measure...” vs. “Using story points or ideal days to measure productivity is a bad idea because it will lead the team to gradually inflate the meaning of a point...”
With all this confusion Michael wonders what are story points? How do you introduce to people new to Agile and Scrum.
Dan Rawsthorne, replies:
- A Team usually WANTS Velocity to be a productivity metric in order to
talk to the outside world about "how fast" it is. - Velocity is only a meaningful metric if Story Points remain constant over the life of a project. To do that the team must use one or two standard stories that remain the same over the life of the project.
- If “the baseline story is not only consistent within a Team, but across Teams, then Velocity not only measures productivity, but can also be meaningfully compared across
Teams, and is additive within an organization” BTW this reporter strongly argues against this practice: “Misuse of Velocity in Agile Projects” - Once the team has stable Story Points then they can be used in future release planning sessions to get a rough estimate of the work they will successfully complete.
Ron Jeffries, replies: “Story points are a relative measure of the time needed to implement a story, borrowed from XP (as is the notion of story). They are intended to be a way of estimating difficulty without committing to a specific time duration, so that variances in team size or time on task do not affect them” and “Yes, they measure size and complexity. The terms "size" and "complexity" are used to mean "how hard is this in terms of how long it'll take us to do it".”. Finally Ron notes that he (and other experts) no longer see story points as necessary.
Previously on InfoQ: Story Points vs Hours