Wednesday, October 10, 2007

The oracle and Delphi

Yes, Taubes strikes another blow at the epidemiologic stronghold! This time, though, he has a point . . .

Namely, people can be influenced by a strong opinion, especially if they aren't certain and/or multiple people express the same opinion. Peer pressure by any other name . . . it can certainly affect any study that requires expert opinions to fill data gaps.

That's why there's this great thing called the Delphi method. Basically, a survey is sent to a panel of experts (or they are interviewed, whatever your method). They are asked to answer a series of questions. Those answers are compiled for each question (range and mean for numerical data, lists for qualitative answers) and sent back to the panel with a fresh copy of the same survey. The experts can then change their answer based on what other people answered without one loud voice dominating. This process is repeated a few times, simulating discussion. Et voila! a consensus is reached in which everyone has an equal voice. A friend of mine used this method in his MS research and it worked quite well.

3 comments:

Angelika said...

And why is that a problem? - Changing one's opinion when confronted with one that appears to make better sense, seems like a pretty sensible thing to do and not at all unscientific. Why else would scientist bother to meet and talk which each other?

Unknown said...

I do have reservations about the Delphi method. There are individuals who are blessed with an extrodinary ability to convince others of their point of view, whether or not they are correct. I would have you look at tele-evangalists (yes scientist are not that gullible I agree). My point is that you cannot equate the ability to convince with correctness.

Lisa said...

In some ways this is similar to the social psychology concept of groupthink. Putting it simply, people who are making decisions as a group tend to make poorer decisions because the momentum of the group tends to outweigh any controverting evidence, if it is even weighed. JFK's Bay of Pigs invasion is one classic example of groupthink. Apparently after that he assigned one person to be the naysayer in every meeting. Their job was to disagree with and argue against whatever the group consensus was. Although, there is also another social psychology finding that says that when you are put in a position to argue for a weakly held belief, you tend to then hold that belief more strongly after arguing for it. Cognitive dissonance plays a role in it . . . anyway I digress.