The method of cost-estimating whereby the costs of the individual work packages are aggregated to form the full cost-estimate is called:

Parametric estimating uses a statistical relationship between historical data and other variables to calculate an estimate, often for similar projects or activities.

Bottom-up estimating is a highly detailed cost estimation method where the cost of each individual work package or activity is estimated. These detailed estimates are then summed up to determine the total project cost, providing a comprehensive and granular budget.

Expert judgment relies on the specialized knowledge and experience of individuals or groups to provide estimates.

Analogous estimating uses historical data from a previous, similar project to estimate the cost or duration of the current project, often when limited detailed information is available.