Which estimation method uses measurable quantities, such as square footage, to estimate costs?

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

Answer: (C)

Parametric estimation uses a measurable quantity, such as square footage, as the driver for cost. You establish a cost per unit from historical data and then multiply that unit cost by the quantity to get the total estimate. This approach is fast and scalable, especially in early planning when details are scarce. For example, if the cost is calculated as $200 per square foot, a 2,500-square-foot project would be estimated at $500,000. This method differs from bottom-up, which builds costs from detailed components, top-down, which assigns a total budget without tying it to a measurable quantity, and analogous, which relies on the total cost of a similar project without directly scaling by a dimension like square footage.