Estimation Techniques

Abstract

Top-down and bottom-up estimations are important in project management because they provide a way to estimate project costs and durations with different levels of precision.

Top-down estimations are based on high-level assumptions and rough calculations. They provide a rough estimate of the overall project cost or duration, and can be used to quickly determine if a project is feasible. These estimations are usually done early in the project planning phase, before detailed information is available.

Bottom-up estimations, on the other hand, are based on detailed information and calculations. They provide a more accurate estimate of the costs and durations of individual tasks, which can then be combined to estimate the overall project cost or duration. These estimations are done later in the project planning phase, when more detailed information is available.

Using both top-down and bottom-up estimations helps to balance the need for quick, rough estimates with the need for accurate, detailed estimates. The top-down estimate provides a high-level view of the project, while the bottom-up estimate provides a more detailed view. By combining these two approaches, project managers can create a more accurate and reliable estimate of the project costs and durations. Additionally, they can identify areas where more information is needed and make informed decisions about the project scope, resources, and budget.

The goal of this article is to present and investigate different top-down and bottom-up estimation methods as well as providing the reader with knowledge on how to apply a top-down or ground-up approach and when they should be combined or used seperately.