Estimating in Scrum: It’s Not About Perfection, It’s About Alignment
In the world of Scrum, estimating isn’t about predicting the future with perfect accuracy. Instead, it’s about creating alignment within the team, improving predictability, and ensuring everyone has a shared understanding of the work ahead. Think of it as the GPS that helps guide the team through the project—clear enough to keep everyone on track, but flexible enough to handle a few detours along the way.
Estimation in Scrum typically happens at two levels: problem-level estimation and solution-level estimation. Problem-level estimation focuses on the high-level question of “what needs solving?” This is where techniques like T-shirt sizing (Small, Medium, Large, Extra Large) come in handy. By categorizing the effort required for each item, the team can quickly gauge the scope without getting bogged down in the details.
Then there’s solution-level estimation, which zooms in on how to solve the problem. Once the team has a clearer picture of the user story, they shift gears to more specific methods, like Fibonacci numbers or relative estimation, to assess the complexity of the solution. This deeper dive ensures that everyone understands how challenging a particular task might be, and helps align expectations for what can realistically be achieved in a sprint.
One of the most common estimation techniques used in Scrum is the Fibonacci sequence. This quirky set of numbers (1, 2, 3, 5, 8, 13, etc.) is designed to help the team think critically about the complexity of tasks. The larger gaps between numbers encourage discussion and force the team to reflect more deeply on the effort required. It’s a great way to avoid oversimplifying or underestimating the work.
For those just getting started with estimating, T-shirt sizing is an excellent tool, particularly for initial backlog refinement. It’s quick, easy, and gives everyone a general sense of the effort needed. Just imagine you’re picking sizes for your tasks—Small, Medium, Large, and Extra Large—and you’re off to the races. This method is perfect when the team is still in the early stages of understanding the scope of the work ahead.
Another technique that’s popular in Scrum is relative estimation. Instead of estimating in absolute terms (how long will this take?), the team compares user stories to each other. This helps create a shared frame of reference, making it easier to gauge the effort required for new tasks by comparing them to ones that have already been sized. It’s like trying to figure out if a new project is more complicated than the last one—simple, yet effective.
Some teams, though less commonly, use ideal hours or days for estimation. This approach brings time into the mix, and while it can be helpful in certain contexts, it’s often avoided because it can lead to a false sense of precision. After all, Scrum is all about flexibility, and time-based estimates tend to leave less room for adaptation.
Now, let’s be clear: estimates in Scrum are not commitments. That’s one of the biggest traps teams can fall into—turning an estimate into a deadline. Scrum teams should be careful not to get caught up in the illusion of precision. Estimates are guidelines, not guarantees. It’s important that the whole team participates in the estimation process, so everyone’s perspective is taken into account. The diversity of thought and experience in the room can lead to more balanced and realistic estimates.
To give you a concrete example, imagine your team is tasked with building a login feature for an app. During backlog refinement, the team might estimate the task at a “Medium” using T-shirt sizing. This is the problem-level estimate—it gives them a rough idea of how much effort is required, but they haven’t yet dove into the details.
Fast forward to Sprint Planning, where the team begins to break down the user story and discuss the solution. Here, the team might decide that the complexity of implementing OAuth integration bumps the task to a 5 on the Fibonacci scale. This is the solution-level estimate, and it reflects a deeper understanding of the task’s complexity.
As with all aspects of Scrum, estimating is a collaborative process. It’s crucial that the entire team is involved so that everyone’s expertise is leveraged. Estimation should always focus on the value being delivered, not just the effort required. And as the team progresses, estimates should be revisited and refined, reflecting the team’s growing understanding of the work and the product.
So, how does your team approach estimation? Do you have any tips or challenges you’ve faced when estimating work? Let’s share our experiences below!
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