Estimating Work

Estimation Approaches

Story Points

Relative complexity, not time.

Points Complexity

1 Trivial, well understood

2 Simple, minor unknowns

3 Moderate complexity

5 Complex, some unknowns

8 Very complex, significant unknowns

13 Extremely complex, many unknowns

21+ Too big, needs decomposition

T-Shirt Sizing

For high-level estimates.

Size Relative Effort

XS Hours

S 1-2 days

M 3-5 days

L 1-2 weeks

XL 2-4 weeks

Estimation Factors

Consider:

• Complexity: How difficult is the problem?

• Uncertainty: How much is unknown?

• Effort: How much work is involved?

• Risk: What could go wrong?

Estimation Techniques

Planning Poker

• Present the task

• Everyone selects estimate privately

• Reveal simultaneously

• Discuss outliers

• Re-estimate if needed

Three-Point Estimation

Expected = (Optimistic + 4×Likely + Pessimistic) / 6

Reference Stories

Keep calibration stories:

• "This 3-point story took 2 days"

• "This 8-point story took a week"

Common Pitfalls

• Anchoring: First estimate biases others

• Optimism: Underestimating unknowns

• Scope Creep: Original estimate doesn't match final scope

• Ignoring Overhead: Code review, testing, deployment

Tips

• Estimate in ranges, not points

• Include buffer for unknowns

• Track actual vs. estimated

• Re-estimate when scope changes

• Don't estimate in hours (use relative sizing)