When estimating the time for a project, there are different techniques to choose from, depending on the level of detail, accuracy, and reliability required. Analogous estimation uses historical data from similar projects to estimate the time for the current project, but may not account for differences and risks. Parametric estimation uses mathematical formulas or models to estimate the time based on the relationship between variables, such as size, complexity, and productivity. However, it may not capture qualitative factors and uncertainties of the project. Three-point estimation is useful when there is a high degree of uncertainty or variability in the project, as it uses three estimates for each task: the most optimistic, the most pessimistic, and the most likely. It then calculates the expected time using a weighted average formula, such as PERT (Program Evaluation and Review Technique). This technique may require more time and effort to obtain the estimates.