Final answer:
The two major categories of estimating project time and costs are macro and micro estimates. Macro estimates provide a high-level overview, while micro estimates are more detailed and specific. Ways to create estimates include analogous, parametric, bottom-up, and three-point estimating methods.
Step-by-step explanation:
The two major categories of estimating project time and costs are:
- Macro estimates: These estimates provide a high-level overview of the project, focusing on the overall scope, timeline, and budget. They are usually used in the initial planning stages and are less detailed and precise.
- Micro estimates: These estimates are more detailed and specific, focusing on individual tasks and components of the project. Micro estimates are used as the project progresses and are updated regularly to reflect any changes or new information.
Ways to create estimates
Macro estimates:
1. Analogous Estimating: This method uses historical data from similar projects to estimate the time and costs of the current project. It relies on comparing the current project with past projects of similar size, complexity, and scope.
2. Parametric Estimating: This method involves using statistical relationships between variables to estimate project time and costs. It uses mathematical models and formulas based on historical data to calculate estimates.
Micro estimates:
1. Bottom-up Estimating: This method involves breaking down the project into smaller tasks or work packages and estimating the time and costs for each individual task. The estimates are then aggregated to get a total project estimate.
2. Three-Point Estimating: This method takes into account the best-case, worst-case, and most likely scenarios for each task. By assigning probabilities to these scenarios, a weighted average can be calculated to provide a more accurate estimate.