Three-point estimation is useful in situations where there is a high degree of uncertainty and risk involved in the project, and when it is difficult to make accurate point estimates. It allows project managers to identify the range of possible outcomes for each task, and to make more informed decisions about resource allocation, project timelines, and overall project feasibility.

It considers three estimates instead of one.

  • TM or cM : normal Estimation
  • TO or cO : Optimistic estimation
  • TP or cP : Risk loaded estimation

Triangular distribution / Simple Average tE

(tO + tM + tP) / 3.

Beta distribution/PERT/weighted Average cE

(cO + 4cM + cP) / 6

An example of Three-point estimation would be a software development project that involves developing a new feature for an existing application. The development team estimates that

  1. the task will take 10 days in the best-case scenario,
  2. 14 days in the most-likely scenario, and
  3. 20 days in the worst-case scenario.

By considering the range of possible outcomes, the project manager can make more informed decisions about resource allocation and project timelines

Three point Estimate Example

Three-point estimation also allows project managers to calculate the expected value and the standard deviation for each task, which can be used to make more informed decisions about risk management and to identify potential areas of concern. However, it also requires more effort and resources to conduct, as it involves creating multiple estimates for each task or activity. Additionally, it is important to ensure that the estimates are based on sound assumptions and that the team members involved in the estimation process are experienced and knowledgeable about the task or activity is estimated.


Analogous Estimation

Bottom-up Estimation

Three-point Estimation

Parametric Estimation

Project Estimation (Video Explanation

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