Accurate Estimations with the Dephi Method

Written by: Rupen Sharma, PMP • Edited by: Michele McDonough
Published Oct 6, 2009

It is common to use expert opinion in project activities, such as while estimating. However, experts usually disagree! As a project manager, you need to channel expert thought in some manner, like by using the Delphi Method, that they reach a consensus. Then, you can make an informed decision.

Introduction

The Delphi Method is an information gathering technique that was created in the 1950s by the RAND Corporation. The Delphi Method is based on surveys and makes use of the information of the participants, who are mainly experts. By using this method, you can get qualitative and quantitative results. The expert surveys are conducted over multiple rounds until a consensus is reached. After each round, feedback is provided, which encourages convergence of thought. A key point to note about the Delphi Technique is that while gathering thoughts, the participants do not know who the other participants are. Hence, participants are not influenced by others taking part in the process.

Uses of the Delphi Method in Project Management

As you might already suspect, the Delphi Method has many uses in project management. You can use the Delphi Method for any activity that requires the convergence of expert thought, such as in:

Risk Management: For identifying risks and quantifying risks.
Time Management: For estimating stories or work activities.

PMP Exam Tip: The Delhi Method (Technique) is a recommended for Risk and Time Management. It is common to see a question on the Delphi Technique in the PMP exam.

Example of Using the Delphi Technique in Estimation

Assume you need to estimate for project activities for an Agile software development

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project. In Agile projects, each project activity that gives the client value is called a story. Accurate estimates for stories or activities are crucial to determining the critical path. Therefore, you’ve hired two consultants and have a project architect within the team to provide expert guidance.

Mike Cohen, the Agile Guru, developed a technique based on the Delphi Method. He called it Planning Poker. In this technique, each story is estimated individually and if there is consensus then the estimates are taken. If there is disagreement, people share their thoughts and the estimation enters a second round. This is repeated until the estimation for the story has reached a consensus.

Note: Mike Cohen has a very good book on Agile Project Estimation called Agile Estimating and Planning. It is a must read for ScrumMasters and anyone involved in Agile Project Management.

Typically, only experts participate in the Delphi Method. However, in project estimation, you should encourage the team to participate in the estimation. This ensures greater ownership and is typical characteristic of SCRUM teams. Even if you are not using Agile, the Delphi Technique can be used to get more accurate estimates.