In antiquity, Delphi, a village in central Greece, was the principal sanctuary and oracle of the god Apollo. The oracle's advice about religion, morality, commerce, and colonial projects, spoken by a priestess in a trance, was widely sought by individuals and the Greek states.
Today, we no longer seek the answers to momentous questions from priestesses. Instead, we turn to consultants or experts. But we don't seem to have the same level of confidence in our experts as the ancient Greeks had in their oracles because we often call in another expert and not surprisingly we get another answer. We then consult ten experts and get twelve answers! We need a method for helping experts (and others) home-in on a high quality, agreed conclusion.
The traditional response to this is to lock the experts in a room and refuse to let them out until they come up with 'the' answer. In reality, it is difficult to get all the experts together at the same time, time is usually limited because of other commitments, there is limited reflection, and the stronger members of the group will often ignore the opinions of the less forthright members.
Most group processes will usually give an answer that is of a higher quality than would be achieved individually, but the Delphi consultation process does not need to have the experts in the same room or have them consider the problem at the same time. Because of this it is ideally suited for use on the Internet or through e-mail messages.
The following is a summary of how the process works:
Steps 2 and 3 are repeated for two more rounds unless agreement has already been reached.The following example will give you an idea of how the process works in practice and can also be used as an exercise for teaching the Delphi consultation process.
Fill a large glass or transparent plastic jar with beans (having counted them first) and invite the 'experts' to individually estimate, to the nearest 50, the number of beans there are in the jar. If the experts are not in the same room, you will need to send a picture of the jar via email.
The experts return their estimates to you...
...and then you collate and rank the results:
You then identify the middle, or median, value which divides the range of estimates in half. If there were an odd number of values, the middle value would be the median. But in this case there is an even number, so you have to use the average of the middle two values (estimates 4 and 5)
Both these estimates are 2500, so the median value is also 2500.
You also identify the interquartile range (IQR) which contains the middle 50 per cent of the answers. In this case, estimates 3, 4, 5 and 6 make up the middle 50 percent, so the interquartile range is from 2000 to 2500.
This information is then fed back to the experts in the following format:
The collated responses to this form are then given to everybody as shown below:
The results and arguments are collated again and are presented to the experts for their final answer:
Having considered the counter arguments, the respondents make their last forecast and return it for the final collation, which in this case might give a median of 2250 and an IQR of 22002400. This is then said to be the consensus for the Delphi consultation process.