Analogous estimation technique:
It is a comparison technique where we look at a similar activity performed before. If more data is available, the better the estimate will be.
Parametric estimation technique:
Parameters from previous similar activity is taken. E.g. Previous activity took 5 days and it had 3 resources working on it, 10 hours daily. This method is more accurate then analogous estimation
Three-point estimation technique
It is used when there is a great deal of uncertainty about duration. We use these parameters and use in the formulas below.
M = most likely | O = optimistic | P = pessimistic | E = expected duration
- Triangular Distribution: E = (P + M+ O) / 3
- Beta Distribution (also called PERT - Program evaluation and review technique): E = (P + M(4) + O) / 6
Beta Distribution is preferred in cases where we have a lot of historical data. When there is no historic data, only with guesses, use Triangle Distribution.
Using these duration estimation techniques, you can get near-to-accurate duration value. It is much better than just guessing a wrong duration, which will negatively effect the project end date