Expert assessment Using expert judgement, one may estimate time by relying on the knowledge and expertise of subject matter experts. For instance, you may ask a construction manager with extensive expertise to make an estimate based on their understanding of the sector if you’re trying to estimate the time of a construction project. While this method may be helpful for projects with many variables and complexity, it may also be biased and only partially objective.
Bottom-up estimating A project is divided into smaller, more manageable components using the bottom-up estimating approach. Each component’s time, resources and costs are estimated. This method enables more precise estimation by considering the specifics of each item and not just using high-level assessments. By identifying possible risks and challenges early on in the project, the bottom-up approach helps prevent potential problems.
Top-down estimating This approach uses high-level estimations to calculate the total time, money and resources needed for a project. It depends on assumptions and generalisations rather than thoroughly examining each project component. This method may be less accurate, but is often quicker and less resource-intensive than bottom-up estimation. A top-down assessment is helpful for projects with a low degree of complexity, where the scope and needs are clear-cut and straightforward.