When I was a project manager in the software industry I dreaded going to the engineers to ask how long their tasks would take. They would look at me with a pained expression on their face and come up with “helpful” phrases such as “Well, how long’s a piece of string!” They were concerned any estimate would be taken as a commitment. The Delphi Technique is one solution to this problem as it uses a number of knowledgeable people to calculate the estimate together.
The process takes place over a number of steps. During each step a facilitator asks each person to submit their estimate of how long the task will take and give a justification for their figure. Results from a group can be skewed towards the thoughts of dominant individuals. To remove this bias everyone submits their ideas anonymously. The facilitator then collates the information together and shows the results back to each person as a histogram, showing the reasons for the upper and lower quartile estimates. This process is repeated usually two more times. What should happen is that the estimate converge. On the final pass the average of the estimates is taken as the prediction.
In Robert K Wysocki’s excellent book, Effective Project Management, there is an demonstration of the effectiveness of the Delphi Technique. The author attends a training seminar and the trainer asks everyone to write their weight down on a piece of paper. She then uses the Delphi process to come to an estimate of the group’s average weight. Unbelievably it is only two pounds off the actual average!
If you’re fed up of hearing phrases asking you the length of strings, try the Delphi Technique, it really does work.
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