Top-down Work Package Estimation

Here is a breakdown structure diagram example.

Idea: Allocate proportions of an effort estimate to different activities of the project

Inputs: Main project activities (high level design) and earlier project data on efforts spent for activities

Outputs: Rough work breakdown with corresponding effort estimates

Advantages: Takes into account integration, configuration management and documentation costs (e.g. algorithmic models seldom take)

Disadvantages:  Underestimating the difficult low-level technical problems