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Delphi Estimation Technique


Introduction :

Delphi technique is quite an old but efficient forecasting method. It follows an interactive approach which relies on exchange of ideas. The team is composed of a group of experts in their respective domains, who answers the queries in two or more rounds. Every time a facilitator provides a summary of the collected ideas, which is revised by the experts if required. The process of opinion and revaluation goes on until a final consensus is reached.

Delphi technique relies its assumption on the fact that assimilation of ideas from a structured group leads to a productive outcome.

Features of Delphi Technique :

Following are the key aspects of a typical Delphi technique:

  • Anonymity of participants :The identity of the participants taking part in the group are kept anonymous. This prevents any kind of ego clashes or further arguments.
  • Structuring information flow :This process aims at eliminating unnecessary and irrelevant content, thus forming a structured flow of information.
  • Regular feedback -Participants keep providing feedback on the responses of others, that facilitates further improvement.
  • Role of the facilitator -Facilitator is the one who monitors the Delphi method. He is responsible for recording the opinion of the experts. He distributes the questionnaires and the experts offer their views. Responses are then collected and analysed to find out the common views. The process continues until a final decision is attained.

Delphi Technique for Software Estimation :

In software estimation, the project specifications are allotted to the experts and they convey their views/opinions about the same. The total number of experts chosen depends on their availability and the size of the project. Delphi in software estimation takes into account the following key points :

  • Expert's Selection
  • Briefing about the project to the experts
  • Gathering an idea/estimate from the experts
  • Assimilate the ideas and finalize it

Selection of Experts :

Expert selection must be based on the relevant amount of experience they have in software development. The experts can be within or without the organisation. The number of experts varies according to their availability in the required knowledge domain, complexity involved in the project etc.

Briefing Experts :

Once the team is set, it is time to brief the experts regarding the various aspects of the project like objectives of the estimation, explaining the scope of the project, competition involved in the project, estimated deadline and expected deliverables from the experts. According to the information , the experts prepare their schedule and devise plan to carry forward the software estimation.

Gather idea/estimate from the experts :

Based on the inputs provided, the experts offer an approximation about the size, effort and time to be allocated to the project.

Expert Name Size Effort
Expert 1 x K
Expert 2 1 A

Assimilation of ideas :

Now when the estimates are defined, we can arrive at a conclusion to combine these estimates. Based on high and low estimates, an average estimate can be drawn, which can be actually used to serve the intended purpose.

Advantages of Delphi Technique :

  • A useful technique in the absence of experts within the organisation, as Delphi allows hiring experts from external sources with required domain knowledge for the project.
  • It is a quick technique to arrive at an estimate.
  • Delphi technique is popular for its simplicity

Disadvantages of Delphi Technique :

  • Sometimes it becomes difficult to find and analyse the right expert.
  • Difficulty in deciding the number of experts required.
  • The estimates derived, are not auditable.
  • This technique can only estimate the size and effort of the project but not the time.

Conclusion :

Out of many other techniques available for software estimation, Delphi is an easy alternative. Every estimation technique offers its own ways of solving issues, hence a wise selection is needed as per the project requirements. This shall deliver the best results.