Which statement best describes the Top-Down estimation approach?

Which statement best describes the Top-Down estimation approach?

• A. Breaks project into discrete parts and estimates each
• B. Uses historical data to form estimates for entire project
• C. Requires detailed design before estimates
• D. Relies on expert judgment for the entire project

Answer: (B)

Top-down estimation starts with an overall project cost derived from historical data, benchmarks, or parametric relationships for similar projects. Rather than breaking the project into components and estimating each part separately, you establish the total cost first and then allocate it to subsystems if needed. This approach is fast and useful in early design stages when details are scarce, allowing quick budgeting and feasibility checks. It may be less precise because it relies on comparisons to past projects and may miss differences in scope, but that trade-off is offset by its speed and broad perspective.

Top-down estimation starts with an overall project cost derived from historical data, benchmarks, or parametric relationships for similar projects. Rather than breaking the project into components and estimating each part separately, you establish the total cost first and then allocate it to subsystems if needed. This approach is fast and useful in early design stages when details are scarce, allowing quick budgeting and feasibility checks. It may be less precise because it relies on comparisons to past projects and may miss differences in scope, but that trade-off is offset by its speed and broad perspective.