Overview

• What you’ll learn: Why estimation matters in Scrum, common estimation techniques (Story Points, T-Shirt sizing, Planning Poker), the #NoEstimates movement, and how estimation abuse undermines Agile.
• Prerequisites: Lesson 31 — Definition of Done.
• Estimated reading time: 14 minutes

Introduction

The Scrum Guide does not mandate estimation. It says that Developers “select items from the Product Backlog to include in the current Sprint” and that “selecting how much can be completed within a Sprint may be challenging.” Estimation is a tool that teams use to make this selection easier — but it is not a commitment.

Common Estimation Techniques

Story Points

Story Points measure the relative complexity, effort, and uncertainty of a PBI compared to a reference item. They use a Fibonacci-like sequence (1, 2, 3, 5, 8, 13, 21) to reflect increasing uncertainty at larger sizes.

T-Shirt Sizing

Items are categorized as XS, S, M, L, XL. Less precise than Story Points, but faster for rough estimation during backlog refinement.

Planning Poker

Team members independently estimate each PBI by showing a card simultaneously. Differences trigger discussion. This prevents anchoring — where one person’s estimate influences everyone else.

Flow-Based Forecasting

Instead of estimating individual items, measure how many items the team completes per Sprint (throughput). Use historical data to forecast when future work might be done. No estimates needed for individual items.

The #NoEstimates Movement

#NoEstimates argues that estimation is often waste — time spent estimating could be spent building. Instead of estimating, break work into similarly-sized small items and use throughput data for forecasting. This works well for mature teams with consistent item sizing.

When Estimation Goes Wrong

Key Takeaways

• Estimation is a tool for Sprint Planning, not a commitment or a contract.
• Story Points measure relative complexity, not hours. T-Shirt sizing is a quick alternative.
• Planning Poker prevents anchoring bias by having everyone estimate independently.
• #NoEstimates works for mature teams that can break work into consistently small items.
• Estimation abuse (converting to hours, comparing teams, using as performance metrics) undermines Agile.

What’s Next

Congratulations — you have completed Module 4: Scrum Artifacts & Commitments! In Module 5, you will explore Kanban for Scrum Teams — optimizing flow through visualization and WIP limits.