View source for Basic estimation techniques

===Expert Judgment===
This technique is quite simple and consists in obtaining the judgment of a group or a person with specialized education, knowledge, skill, experience, or training, in the subject that has to be estimated. The expertise can either be provided in the corporation or externally, for example by turning to a professional consulting agency. During the process, it is a good idea to provide documents, data and other relevant information that can help the involved parts with estimating accurately. 
An example of carrying this method out could be having a group of experts to estimate how much the cost for a specific construction material will fluctuate in the next five years. The group will have an open discussion and will eventually at the end agree on what they believe to be the most valid prediction. The problem with doing so is that there could be a tendency to be persuaded by the majority opinion or the members with the greatest authority on the matter.<ref name="Delphi_Method"> ''Helmer, O. (1967). Analysis of the future: The Delphi method. The RAND Coroporation, Santa Monica, California.'' </ref>  

A well-known method to overcome these issues is the '''Delphi method'''. According to Helmer (1967), the purpose of this method is to obtain the most reliable consensus of opinion from a panel of selected experts, by questioning them individually around a central subject in a series of rounds, without having the experts confronting each other directly. After every iteration, a host presents the given answers to the group anonymously, thus encouraging the experts to revise their judgement, based on factors other have brought up and that they maybe did not have into consideration during the previous iteration. At the end of the process, the answers are expected to converge towards a more reliable and unbiased estimate for the object of interest.<ref name="Delphi_Method"></ref>