Estimating the effort required to deliver product features and epics is one of the toughest yet most critical responsibilities for product managers and product owners. Being able to accurately estimate deliverables directly impacts the team’s ability to plan sprints, meet commitments, and delight customers with new capabilities.
Traditionally, product managers made guesses or relied on bottoms-up estimates from developers. However, agile frameworks provide proven estimating techniques that product managers can leverage to size up deliverables more accurately.
In this post, the first in a two part series, we will explore some of the most popular agile estimating methods used by scrum teams – story points, planning poker, and t-shirt sizing. While originally created for agile software development environments, these collaborative techniques are extremely useful for product managers to estimate projects and features, regardless of development methodology.
Learning when and how to apply these methods will empower product managers to:
- Quickly estimate relative effort and complexity for prioritization and planning
- Encourage team collaboration and consensus building
- Develop a shared understanding of deliverable objectives and challenges
- Calibrate estimates based on historical data over time
- Go beyond guesswork and estimate projects with confidence!
Methods to Accurately Estimate Deliverables
Let’s take a closer look at how product managers can leverage these agile estimating frameworks to their advantage.
Story Points
Story Points are a popular agile estimating technique used to estimate the overall size and difficulty of user stories in product backlogs. They provide a numerical unit to represent the relative effort required to implement each user story, acting as an abstract measure of complexity and workload rather than time.
The process involves the agile team discussing each user story during backlog refinement sessions and collectively agreeing on the number of points it should be assigned based on factors like:
- Level of complexity – Is there complex logic or algorithms involved?
- Amount of work – Will it require significant development and testing effort?
- Risk and uncertainty – Are there many unknowns or dependencies that make the work tricky to estimate?
- Story size – Number of functional requirements and scope of functionality. Larger stories tend to have more points.
Teams use a non-linear scale like the Fibonacci sequence (1, 2, 3, 5, 8, 13, etc.) to assign points, reflecting the inherent uncertainty in early project stages. The abstract nature of points lets the team estimate effort without being bogged down by time units.
Over the course of multiple sprints, the development team tracks the actual time taken to complete stories with different point values. This helps calibrate point values by correlating them to hours or days of real work completed. For example, the team determines stories worth 5 points that take about 2 days to implement. This conversion helps with longer-term planning and forecasting using the point scale.
Key benefits of story points include building team collaboration, reducing conflict over estimates, maintaining velocity trends over time, and allowing for early uncertainty without precise time predictions.
Planning Poker
Planning Poker is another agile estimating technique, very similar to the Story Points approach, however it injects an engaging, game-like element into the often tedious user story estimation process. It builds on the Story Points approach but gets the whole team involved through active participation and discussion.
To start, each team member receives a deck of planning poker cards numbered according to the chosen scale – often the Fibonacci sequence (1, 2, 3, 5, 8, etc.). The product owner or scrum master reads the user story description to the group. Individuals then silently pick a card reflecting their estimate and reveal their choice simultaneously.
If estimates converge, the team accepts it as the story’s point value. However, divergent estimates signal the need for more clarification and debate. Team members explain their rationale and assumptions, then re-estimate after gaining new perspective from others. Multiple estimation rounds may occur before reaching consensus.
Planning poker promotes shared understanding of each user story’s scope and complexity. The collaborative process reduces individual biases through group learning and discussion. Having to physically pick and reveal estimate cards adds an engaging game element that fosters active participation. The visual cue of seeing everyone’s estimated cards accelerates reaching agreement.
Planning Poker builds teamwork, communication, and estimation skills. The light-hearted activity of playing cards lowers tension while developing the team’s ‘estimation muscle’. It provides an efficient yet insightful technique for teams to size backlog items and identify gaps in understanding before implementation begins.
T-Shirt Sizes
The T-Shirt Sizes technique provides a quick and intuitive way for agile teams to relatively size user stories during backlog grooming or sprint planning. It acts as a lightweight starting point before diving into more detailed story points or time-based estimates.
To begin, the team agrees on a set of shirt size categories that represent increasing levels of effort and complexity. A typical scale is XS, S, M, L, XL but some teams may customize their sizing labels.
During backlog refinement or sprint planning, the group assigns a t-shirt size to each new user story based on initial analysis and high-level discussion of scope and complexity. For example, a story involving minor UI text changes may be XS while a sizable story requiring new algorithms and complex logic could be XL.
The abstract nature of using shirt sizes, rather than concrete time units, encourages rapid estimation and relative ranking of backlog items. The team can breeze through a sizable backlog quickly to create an initial priority order before follow-up estimation occurs.
After the backlog has shirt size designations, the team can employ more precise estimating with story points or hours for higher priority items during subsequent planning. But T-Shirt Sizes provide an excellent starter method for roughly ordering the backlog without getting bogged down in details upfront.
The technique builds teamwork as members discuss and align on the scope represented by each shirt size. T-Shirt Sizes enable lightweight, rapid backlog estimation to set the stage for more fine-grained techniques later on high-priority items.
Conclusion
Estimating product deliverables is a complex endeavor filled with uncertainty. While there are no silver bullet solutions, leveraging collaborative agile estimating techniques can help product managers develop more accurate forecasts.
Story points, planning poker, and t-shirt sizing each have their merits in encouraging team conversations, building consensus, and relatively sizing product features or projects. Over time, historical data can be used to calibrate estimates and enhance precision.
The key is to experiment with these techniques and determine which ones work best for your team and organization. Consider blending practices like using t-shirt sizing for initial estimates, followed by planning poker for more detailed sprint planning.
While these methods originated for agile software development, product managers can adapt them to estimate projects beyond just engineering efforts. Refine the techniques to suit your needs.
Precise estimates directly impact the ability to set realistic roadmaps, ship value to customers faster, and delight them with new capabilities. Leveraging collaborative agile estimating techniques is a proven way for product managers to move beyond guesswork and estimate projects with greater confidence.
Join us in Part II of this series on estimating tools and frameworks, which will review Three-Point Estimating (PERT), Comparative Sizing, Complexity Points, and more…