What type of estimate is based on the cost of performing similar work in the past, adjusted for current job conditions?

Analogous estimating, also called top-down estimating, directly leverages historical cost data from comparable completed projects as its primary input. It then scales and adjusts that historical figure based on differences in size, complexity, and current market conditions, making it faster to produce but less precise than detailed bottom-up estimating methods.

Parametric estimating uses statistical unit-rate relationships such as cost per square foot or cost per unit rather than direct comparison to a single historical project's total cost.

Engineering or bottom-up estimating builds cost from detailed quantity takeoffs and applied unit prices, not from an overall historical project cost comparison.

Ledger estimating is not a recognized standard estimating methodology in project management or construction cost engineering practice.

PERT is a three-point technique used for schedule duration estimation, not for deriving cost estimates from past similar project data.