Agile 101: Story Point Estimating

Tom Mochal, PgMP, PMP, TSPM is the president of TenStep, Inc., a methodology development, consulting and training company. Tom won the Distinguished Contribution Award from the Project Management Institute for his work spreading knowledge of project management around the world. He is a speaker, lecturer, instructor and consultant to companies and organizations around the world.

  Agile   Estimating   Scrum   ProjectsAtWork  

Agile projects incorporate a number of techniques that are not easily transferable to traditional waterfall projects. One technique is the estimation of the size of user stories with abstract story points, and the use of story points to determine how much work can be completed in an iteration.

Agile project teams implement a set of user stories in short iterations. The user stories are generally pulled from the Product Backlog in priority order. Because the team cannot implement every user story in one iteration, there can be only so many user stories pulled for each iteration. The number of stories depends on the amount of effort it takes to fully implement each story.

How do Agile teams estimate the size of each user story? One familiar technique is to estimate the effort hours requested to implement each user story. The team does not need to be totally accurate, so they can provide rough estimates — maybe in 25 hour increments. In other words, it is only important to know if the user story will take 75 hours or 100 hours. It is not important to know if it is actually 77 hours or 93 hours. Estimating in increments makes the estimates easier and will tend to even out over multiple user stories.

Although estimating by effort hours is very common in traditional projects, it is actually not used very often on Agile projects. A much more common option is to use …

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