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

1. Present the task
2. Everyone selects estimate privately
3. Reveal simultaneously
4. Discuss outliers
5. 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

1. Estimate in ranges, not points
2. Include buffer for unknowns
3. Track actual vs. estimated
4. Re-estimate when scope changes
5. Don't estimate in hours (use relative sizing)