Story Points
Story points are estimation units used to assess the amount of work required to complete each item in the product backlog. Additionally, they serve as an abstract measure defined by the team, meaning they hold value only within that specific team and project. This estimation method helps the team evaluate, understand, and compare tasks based on the effort required to complete them. Moreover, story points represent a relative estimate, not an absolute measure of time. Instead, they indicate the effort needed to complete an item in relation to others. When the team uses them they must consider factors such as task complexity, required time, dependencies, risks, and necessary resources.
Using Story Points for Product Backlog Prioritization
When organizing and prioritizing the product backlog, story points can be valuable in facilitating the process. Since the team assigns to each task a specific number of story points, it becomes easier to determine the required effort for completion. However, it is crucial to remember that a story point does not equate to an hour. Many teams mistakenly attempt to convert story points into hours, which is incorrect. They only help determine whether a task requires twice or three times the effort of the smallest item. That said, the smallest item does not necessarily take just one hour to complete.
Key Factors to Consider When Using Story Points
When considering using stories points is important to consider factors, such as:
- Size – The team evaluates the work in terms of quality assurance metrics and the definition of done. The team must determine whether external reinforcements are necessary, as outside resources can introduce challenges and delays.
- Knowledge – The team considers whether this is the first time they are working on a particular item or if they have handled similar tasks before.
- Complexity – The team assesses the difficulty level of completing the item.
- Risk – The team examines potential threats and opportunities that could arise while executing the task.
Advantages of Using Story Points
Story points provide a clear understanding of the project’s overall scope by evaluating each task individually. Some key advantages include:
- Breaking down projects into manageable items – Story points enable teams to analyze each task in detail, determine necessary resources, and decide whether further breakdowns are required.
- Improving estimation accuracy – Since multiple team members contribute their perspectives, the final estimate tends to be more realistic and aligned with real-world execution.
- Encouraging collaboration – Teams discuss and estimate tasks together, fostering knowledge-sharing and problem-solving.
- Optimizing sprint planning – Teams select a set number of backlog items per sprint. Story points help teams gauge the effort required for each task, ensuring they do not overcommit during a sprint.
- Identifying potential roadblocks – By analyzing the required effort in advance, teams can anticipate challenges and start tasks earlier if necessary.
How to Estimate Using Story Points
Although story points offer a more viable estimation metric compared to other methods, they are not always easy to implement due to their inherent complexity and the need for prior experience. Below are best practices for estimating with story points:
Involve the Entire Team
First, ensure that all team members understand what story points are and how they influence estimation calculations.
Determine the Smallest Item Equivalent to One Story Point
To establish a baseline, the team must identify the smallest backlog item. Then the team must assign one story point to this item. This reference point will help compare and estimate other tasks.
Choose a Story Point Scale
The most common approach is to use the Fibonacci sequence (0,1,2,3,5,8, etc.), where each number is the sum of the two preceding ones. Alternatively, teams can opt for a modified Fibonacci sequence or powers of two.
Use Planning Poker
A dynamic way to estimate story points is through Planning Poker. In this technique, each team member receives a deck of cards with Fibonacci numbers. One person reads the task details, and team members select a card representing their estimated effort. Everyone reveals their cards simultaneously, followed by a discussion to reach a consensus.
Determine the Team’s Velocity
At this stage, the team should define how many story points can be completed per sprint, which represents their velocity. Additionally, teams should clarify their sprint goals to ensure they select the right tasks to achieve both sprint and project objectives.
Continuously Improve the Estimation Process
After each sprint, teams should assess the number of story points completed and evaluate the accuracy of their estimations. If estimates were over or underestimated, teams should refine their approach to improve future sprints.