Exam CAPM Topic 3 Question 480 Discussion

According to the PMBOKGuide, Bottom-up estimating is a method of estimating project duration or cost by aggregating the estimates of the lower-level components of the Work Breakdown Structure (WBS).
* The Process: When the information is not available at a high level or when a high degree of accuracy is required, the project team starts at the most granular level-the work package. Each work package is estimated for cost or duration, and these estimates are then " rolled up " to higher levels (control accounts and eventually the total project).
* Accuracy and Cost: This is typically the most accurate form of estimating because it involves the people actually doing the work. However, it is also the most time-consuming and costly technique to perform because of the level of detail required.
* Prerequisite: This technique relies on a well-defined WBS. If the work cannot be decomposed into work packages, bottom-up estimating cannot be performed effectively.
Analysis of Other Options:
* A. Three-point estimating: This technique uses three values (Optimistic, Most Likely, and Pessimistic) to calculate an estimate. While it can be used at the work package level, the act of " totaling work packages " is specifically the definition of bottom-up estimating.
* B. Parametric estimating: This uses a statistical relationship between historical data and other variables (e.g., square footage in construction) to calculate an estimate. It is a " top-down " or mathematical approach rather than an aggregation of individual work packages.
* D. Data analysis: This is a broad category of techniques (such as Alternative Analysis or Reserve Analysis) used throughout the project. It is not a specific estimating method for aggregating work package totals.