Agile Estimation Drift: How to Maintain Reference Stories
Six months ago, team estimated "add form validation" at 5 points. Today, same complexity story gets 3 points. Baseline drifted without team realizing. Velocity chart shows improvement but actual throughput unchanged.
What Causes Estimation Drift
- Team skill improves: What was complex became routine
- Forgotten baseline: No reference stories to compare against
- New team members: Bring different baseline from previous team
- Pressure to inflate velocity: Unconsciously deflate estimates to "look faster"
Quarterly Calibration Ritual
- Pull 5 reference stories from 6 months ago
- Re-estimate blind (don't show original)
- Compare new estimates to original
- Discuss: Skill improvement or drift?
- Update references if needed
Maintaining Reference Story Library
- Tag 3-5 stories per point value as "reference"
- Document in team wiki with links to Jira
- Review during onboarding for new members
- Recalibrate quarterly