Quick Verdict
Analogous estimating uses actual data from a similar past project, adjusted by expert judgment. It is fastest early in planning when detailed scope is not yet available. Parametric estimating applies a known unit rate to a measurable quantity (e.g., $150 per square foot x 2,000 square feet). It is more precise when reliable rate data exists. Analogous is a whole project comparison. Parametric is a mathematical calculation. The best approach often combines both: analogous for the initial estimate, parametric to validate and refine.
Quick Verdict
Use analogous estimating when you have a comparable past project and need a fast, top down estimate early in planning. Use parametric estimating when reliable unit rates exist and the scope can be expressed as a measurable quantity. For the most accurate results on complex projects, use both: analogous for the initial ballpark and parametric to refine as scope details emerge.
Common Questions About Analogous vs Parametric Estimating
Can I use both analogous and parametric estimating on the same project?
Yes, and this is common practice. Use analogous for the initial order of magnitude estimate during project initiation. As scope details emerge, switch to parametric for work packages where reliable unit rates exist. Compare the two estimates to calibrate confidence.
Which method is better for the PMP exam?
Both appear on the PMP exam. Know that analogous is a top down, expert judgment based technique used early in planning. Parametric is a mathematical technique that requires quantifiable scope and historical unit rates. The exam tests whether you can select the right technique for a given scenario.
What if I have neither historical data nor unit rates?
Use three point estimating (optimistic, most likely, pessimistic) with expert judgment. This produces a range estimate with a standard deviation that quantifies uncertainty. It is the fallback when neither analogous nor parametric is feasible.
