Relative Estimation
Relative Estimation is an agile technique where work items are sized in comparison to each other rather than in absolute units like hours or days, providing faster and more accurate estimates.
Explanation
Humans are generally better at comparing things than estimating absolute values. Relative estimation leverages this by asking teams to compare items: Is this item about the same size as that one? Is it roughly twice as large? This comparative approach is faster, more consistent, and less influenced by individual speed differences.
Common relative estimation techniques include Planning Poker, T-shirt sizing (XS, S, M, L, XL), and affinity estimation (grouping items into size categories on a wall). Story points are the most common unit for relative estimation. A reference story is established as a baseline, and all other items are estimated relative to it.
Relative estimation works because teams can reliably judge that one item is twice as complex as another even if they cannot predict exactly how many hours it will take. Over time, the team's velocity translates relative estimates into predictable throughput, enabling accurate sprint and release planning.
Key Points
- •Compares items against each other rather than using absolute time units
- •Faster and more accurate than absolute estimation
- •Common techniques: Planning Poker, T-shirt sizing, affinity estimation
- •Uses a reference story as a baseline for comparison
Exam Tip
Relative estimation is preferred in agile because it is faster, less contentious, and more reliable than absolute estimation. Teams estimate size, and velocity translates that into time.
Frequently Asked Questions
Related Topics
Story Points
Story points are a unit of measure for expressing the overall effort, complexity, and uncertainty involved in completing a Product Backlog item, used for relative estimation rather than measuring time.
Planning Poker
Planning Poker is a consensus-based agile estimation technique where team members privately select cards representing their estimate, reveal them simultaneously, and discuss differences to reach agreement.
Velocity
Velocity is the amount of work a Scrum team completes in a Sprint, typically measured in story points, used to forecast how much work the team can handle in future sprints.
Most-studied PMP concepts
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Burndown Chart
A Burndown Chart is a graphical representation of work remaining versus time in a Sprint or release, showing whether the team is on track to complete the planned work.
Sprint Review
The Sprint Review is a Scrum event held at the end of the Sprint where the Scrum Team presents the Increment to stakeholders, gathers feedback, and collaborates on what to do next.
Sprint Backlog
The Sprint Backlog is the set of Product Backlog items selected for the Sprint, plus the Sprint Goal and the plan for delivering the Increment.
Timeboxing
Timeboxing is the practice of allocating a fixed, maximum amount of time for an activity, after which the activity stops regardless of whether it is complete.
Resource Leveling
Resource leveling is a resource optimization technique in which adjustments are made to the project schedule to keep resource usage at or below a defined limit, often resulting in a longer project duration.
Risk Register
The risk register is a project document that records the details of individual project risks, including their identification, analysis results, response plans, and current status.
Stakeholder Mapping
Stakeholder mapping is the visual representation of stakeholder relationships, influence, interest, or other attributes using grids, matrices, or diagrams to support analysis and engagement planning.
Cost Performance Index (CPI)
Cost Performance Index (CPI) is an EVM efficiency metric that measures cost performance as the ratio of earned value to actual cost: CPI = EV / AC.
Schedule Performance Index (SPI)
Schedule Performance Index (SPI) is an EVM efficiency metric that measures schedule performance as the ratio of earned value to planned value: SPI = EV / PV.
Part of
Agile & Hybrid
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