3.4.1 Agile Estimation Techniques

Effective estimation in agile environments focuses on relative sizing for near-term planning and forecasting.

• Purpose: Understand relative size for near-term planning and high-level forecasting, not predict exact dates far out.
• Units: Story Points or Ideal Days (relative units). Accuracy vs Precision matters. Provide ranges initially; use probabilistic estimates for high uncertainty.
• Techniques Compared: Planning Poker (builds consensus), T-Shirt Sizes (quick, high-level), Affinity Estimating (fast grouping), Analogous Estimating (uses similar past items), Wideband Delphi (iterative expert consensus). Done by the team doing the work.
• Velocity Calculation: Average points completed over last 3-5 iterations. Use: Forecast iterations needed (Total Points / Velocity ≈ Iterations); Plan capacity for next iteration.
• Pitfalls: Treating as target, comparing teams, assuming constant. Estimate includes all work for DoD. Flow uses Cycle Time x Throughput.