Which estimating method involves estimating costs of each task and then summing those costs to form the overall estimate?

• A. Bottom-up
• B. Top-down
• C. Parametric
• D. Analogous

Answer: (A)

Bottom-up estimating involves estimating the cost of every work package or task in the project and then summing those costs to form the total estimate. This approach matches costs to the actual work, using detailed inputs like labor rates, material costs, durations, and resources for each task, which generally yields the most accurate overall budget when the scope is well defined. Because you build the total by aggregating precise, task-level figures, you also gain clearer visibility into which activities drive costs and how risks may affect the bottom line, supporting a solid cost baseline and more reliable control. In contrast, top-down estimates start from a total we obtain from an expert or historical data and then allocate it to tasks, which is quicker but usually less precise; parametric estimates apply unit costs or productivity factors to quantities and depend on accurate data and valid units; analogous estimates use costs from a similar past project, which can be fast but may be less reliable if the projects aren’t truly comparable.