HKSM
Estimate Range
Present project estimates as ranges, not single numbers. A single precise value can suggest more certainty than actually exists. Because estimates are inherently uncertain, the width of the range should reflect the team's confidence in the estimate.
Key Points
- Use ranges to show uncertainty and avoid a false sense of precision.
- Set the width of the range based on the team's confidence and available information.
- Document key assumptions and risks that influence the estimate range.
- Refine and narrow the range as the team learns more and reduces uncertainty.
Example
During release planning, the team estimates that building the payment integration will take 10-14 days with about 60% confidence, assuming an existing API is stable. After a technical spike confirms compatibility, they adjust the range to 11-12 days with 80% confidence.
PMP Example Question
A product owner asks for a precise delivery date for a complex feature early in planning. What is the best response?
- Provide a single date to build stakeholder confidence.
- Decline to estimate until development starts.
- Give a single-point estimate with a large contingency buffer.
- Offer an estimate range tied to stated assumptions and confidence level.
Correct Answer: D — Offer an estimate range tied to assumptions and confidence
Explanation: Ranges communicate inherent uncertainty and should reflect the team's confidence, avoiding misleading precision early in the project.
