Which method of estimation requires detailed estimates for the work activities outlined in the WBS?

Bottom-up estimation is the correct method for situations requiring detailed estimates for the individual work activities outlined in the Work Breakdown Structure (WBS). This technique involves estimating the cost and duration of each specific task or activity within the project. By assessing each component thoroughly, project managers can accumulate these estimates to develop a comprehensive understanding of the overall project costs and timelines.

This approach is particularly valuable when the project scope is complex, as it provides a high level of accuracy and detail. It allows for a clear identification of resource needs and potential risks associated with each task. Since each work activity is broken down and analyzed individually, this method requires substantial initial effort but ultimately leads to a more reliable and realistic project plan.

In contrast, top-down estimation is more generalized and relies on overall project scope and historical data rather than intricate details about each task. Parametric estimating typically uses statistical relationships and requires existing data to estimate costs and duration, which does not delve into the specifics of individual work packages like bottom-up estimation does. Expert judgment, while valuable, does not inherently demand detailed analysis of all activities in the WBS and may rely more on the opinions and experiences of knowledgeable individuals rather than a systematic breakdown of the project.