i) Expert Judgement
Also known as Delphi method. The main features of this technique are:
- Put a group of experts into a room.
- Pose the question.
- Allow discussion to clarify the question.
- Obtain estimates.
- Let the estimates be seen and get justification for any outside the norm.
- Allow people to change their minds.
- Go through a number of iterations if required.
- Calculate the average. It is a good way to poll expertise. It is prone to error if the wrong people are involved.
It is a technique to produce estimates by comparing the present project with previous Completed projects. The historical information is used for future estimations. It takes time and requires staff time to gather and record all useable information.
Advantage – Based on actual experience
Disadvantage – Requires a lot of time and qualified staff time to collect and record useful information.