estimation-techniques

name	estimation-techniques
description	Apply evidence-based estimation methods (story points, t-shirt sizing, planning poker) to reduce uncertainty. Use when sizing work for sprints or releases.

Estimation Techniques

Master multiple estimation approaches and when to apply each to improve planning accuracy.

Context

You are helping a tech lead and team establish or improve estimation practices. If the user provides historical velocity data or team composition, use it to ground recommendations.

Domain Context

• #NoEstimates advocates (Allen Ward, Daniel Vacanti) argue cycle time and throughput matter more than estimates
• Agile community consensus: estimation is about communicating risk and driving conversation, not prediction
• Evidence from Larson and Fournier: teams that practice estimation develop better intuition about unknowns and dependencies

Key principles:

1. Estimation reveals uncertainty, not destiny: The goal is to surface what the team doesn't know
2. Compare estimates to actuals: Build feedback loops so the team learns its own accuracy patterns
3. Right-size the effort: Different estimation techniques fit different horizons (sprints vs. quarters)

Instructions

1. Choose the horizon: Short-term (sprint) uses story points; medium-term (3 months) uses t-shirt sizing; long-term (roadmap) uses epic sizing with confidence bands
2. For story points: Have team rate relative effort (small, medium, large) against baseline stories. Use Fibonacci (1, 2, 3, 5, 8, 13) to force bucketing
3. For t-shirt sizes: Define S/M/L/XL in terms of days or weeks of effort, plus confidence. "M with 80% confidence" is better than "2 weeks"
4. For planning poker: In real-time estimation, discuss outliers (largest and smallest estimates) to surface hidden risks and assumptions
5. Build a team estimate profile: Track your team's estimates vs. actuals over 2-3 sprints to calibrate, then share with stakeholders
6. Account for unknowns: Always add a "spike" or investigation task if the team says "we don't know what we don't know"
7. Decompose aggressively: If anything is >13 points or >XL, it's probably not understood yet. Break it down

Anti-Patterns

• Treating estimates as commitments: LLMs often present estimates as hard deadlines, not uncertainty ranges. Always say "we estimate 2-3 weeks with 70% confidence, but will know more after the design phase."
• Skipping the "why" in estimation: Teams can assign points without explaining what unknowns exist. Estimates without risk commentary are useless. Always ask "what could make this larger?"
• Ignoring velocity variation: LLMs assume linear velocity, but sprints with deploys, incidents, or learning are different. Account for sprint types (standard, deploy, learning) and show historical variance.
• Estimation without feedback loops: If you don't track actuals vs. estimates, the practice becomes cargo cult. Insist on retrospective calibration every sprint.

Further Reading

• Larson, Will. "An Elegant Puzzle." Chapter on planning, velocity, and confidence bands.
• Vacanti, Daniel. "ActionableAgile: Metrics for Predictability." O'Reilly, 2014.
• Ward, Allen. "Lean Product and Process Development." Lean Enterprise Institute, 2007.
• Cohn, Mike. "Agile Estimating and Planning." Prentice Hall, 2005.