Estimating Software-Intensive Systems: Projects, Products, and Processes

Chapter 12Top-Down Estimating and Allocation

The Top-Down Method is useful for quickly estimating the total resources required for some object (typically a project), and allocating this total to lower-level objects (such as project activities or subsystems). This gives initial estimates for each of the various activities or subsystems. These estimates may be sufficient for early planning. You can also use these estimates to crosscheck estimates prepared using other methods, such as the Bottom-Up Method described in Chapter 11, “Bottom-Up Estimating and Scheduling.”

You can use the Top-Down Method to estimate effort, cost, and schedule (or duration) for project tasks. You can also use it to estimate the project’s average staffing level and staffing ...