PMI-ACP Practice Questions #89
Your Agile team is developing a fitness tracking mobile app. During backlog refinement, the team estimates the following parent user story:
“As a fitness enthusiast, I want to log my daily exercises, so that I can track my fitness progress.”
The team initially estimates the story at 8 story points but later decides to split it into three smaller stories:
- Log cardio exercises – 3 story points
2️. Log strength training exercises – 2 story points
3️. Log flexibility and yoga exercises – 2 story points
A new team member points out that the total now equals 7 story points instead of the original 8, and asks if the breakdown should match the original estimate.
How should the team handle this situation?
A. The total estimates of the smaller stories must add up to exactly 8 story points to stay aligned with the original estimate.
B. The team should re-estimate each smaller story independently, and the total does not need to match the original estimate.
C. The Product Owner should decide the final total since they own backlog prioritization.
D. The team should reassemble the stories into one larger story to avoid estimation mismatches.
Analysis
In Agile, estimation is a continuous process, and teams refine their understanding of user stories as they progress. When a large story is broken down into smaller stories, the sum of the smaller estimates does not have to match the original estimate exactly. The goal of estimation is to improve forecasting and planning, not to force alignment with previous estimates. Each smaller story should be independently re-estimated based on the team’s better understanding. The Product Owner does not dictate story points, and reassembling stories just to match estimates is counterproductive.
Analysis of Options
A: The total estimates of the smaller stories must add up to exactly 8 story points to stay aligned with the original estimate.
This option is incorrect because Agile estimation is not about maintaining consistency with an earlier guess. As the team refines its understanding, estimates may change. Story points should be used for planning and forecasting, not as rigid numbers that must remain unchanged. Agile encourages progressive elaboration, allowing for adjustments as more details emerge.
B: The team should re-estimate each smaller story independently, and the total does not need to match the original estimate.
This is the correct option. When a large story is broken down, the team gains a clearer understanding of each component. Each smaller story should be estimated based on its actual complexity, risk, and effort. The purpose of estimation is to ensure effective planning, not to preserve past numbers. The total may be different from the original estimate, and that is acceptable.
C: The Product Owner should decide the final total since they own backlog prioritization.
This option is incorrect. While the Product Owner is responsible for prioritizing backlog items, story point estimation is a team activity. The development team, not the Product Owner, determines estimates based on their collective understanding of effort and complexity. The Product Owner should not dictate story point values.
D: The team should reassemble the stories into one larger story to avoid estimation mismatches.
This option is incorrect because keeping a large story just to maintain a previous estimate defeats the purpose of breaking it down. Large stories (or epics) are split to improve planning, enable incremental delivery, and make work more manageable. Merging them back together does not solve the issue; it only adds complexity and reduces the team’s ability to deliver value iteratively.
Conclusion
The best approach is Option B, where the team re-estimates each smaller story independently without forcing the total to match the original estimate. Agile estimation is a flexible and evolving process, and the focus should be on improving accuracy and planning, not on maintaining previous estimates.
PMI – ACP Exam Content Outline Mapping
| Domain | Task |
| Product | Refine Product Backlog |
Topics Covered:
- Story points are estimates and may change as understanding improves
- Each smaller story should be independently estimated based on complexity and effort
- The total of smaller stories does not need to match the original estimate
- The Product Owner does not determine story points—estimation is a team activity
- Breaking down large stories improves planning and incremental delivery
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