What Are Scrum Story Points?
A story is the smallest unit of work for a Scrum team, expressed from the perspective of the end-user. Stories are often written as a simple sentence, for example: “As an online banking customer, I want to be able to add payees to my account so I can transfer money.”
Story points in Scrum are units of measurement used to estimate the effort required to complete a story. When planning for an upcoming sprint, Scrum teams use story point estimation to gauge how much effort is needed to develop a new software feature or update.
Why focus on effort instead of hours? The idea is that if you ask two developers how long it will take to complete a story, they may give you two completely different answers. However, if you ask them how much effort a product backlog item will take to complete, they’re more likely to agree.
How do you estimate story points in Scrum?
Scrum story points are usually represented using the Fibonacci sequence, where each number is the sum of the two preceding numbers:
0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144…
Many Scrum and Agile teams now use a modified version of the sequence:
1, 2, 3, 5, 8, 13, 20, 40, and 100
The space between each number makes it easier for Scrum teams to distinguish between them and agree on which one to use.
When using story point estimation, Scrum teams consider the complexity of the story, the potential risks involved, and the familiarity of the tasks. Then, they assign values to the story points using the following steps:
- Choose a previous story as a reference point. Say, for example, you picked base stories with values of two and five respectively — team members can determine a new value of three, as the task being estimated is bigger than the story with two but smaller than five.
- Create a matrix to visualize story point values. Make a row for each number in the Fibonacci sequence. When you assign values to your story points, place them in the corresponding row.
- Play story points planning poker. This Scrum estimation technique helps teams assign values to story points using playing cards to denote the numbers on the Agile Fibonacci sequence. Team members discuss upcoming user stories, then pick the card they feel represents the appropriate value for the story. If everyone chooses the same number, that number is assigned to the story. If even one member chooses a different number, the team discusses the story further until consensus is reached.
Why use story points in Scrum?
Scrum story points are considered to be more accurate than estimating in hours. Greater accuracy enables the product owner to plan sprints more efficiently, ensuring stories are delivered on time.
Story points also consider that not every team member works the same way — one employee could require a day to complete a certain task, while another may only take a few hours. By focusing on effort and doing away with strict due dates, story points take the pressure off team members.
Finally, story points promote teamwork. Estimating story points requires that everyone work together and each team member has a say. This, in turn, leads to happier, more productive Scrum teams.
