Question

Projects are estimated through identification of tasks and allocation of effort to complete the tasks and how to develop a high-level project plan.

Discuss project estimating methods. How do they compare?

Answer 1

Following are the project estimating methods----------

1. Top-Down Estimate-----Once more detail is learned on the scope of the project, this technique is usually followed where high-level chunks at the feature or design level are estimated and are decomposed progressively into smaller chunks or work-packets as information is detailed.

2. Bottom-Up Estimate-----This technique is used when the requirements are known at a discrete level where the smaller workpieces are then aggregated to estimate the entire project. This is usually used when the information is only known in smaller pieces.

3. Analogous Estimating----This technique is used when there is a reference to a similar project executed and it is easy to correlate with other projects. Expert judgment and historical information of similar activities in a referenced project are gathered to arrive at an estimate of the project.

4. Parametric Estimate---This technique uses independent measurable variables from the project work. For example, the cost for construction of a building is calculated based on the smallest variable as the cost to build a square feet area, the effort required to build a work packet is calculated from the variable as lines of codes in a software development project. This technique gives more accuracy in project estimation.

5. Three-point Estimating----This technique uses a mathematical approach as the weighted average of an optimistic, most likely and pessimistic estimate of the work package. This is often known as the PERT (Program Evaluation and Review Technique).