The adequacy of Tetlock's control groups (was Re: [asa] Trees don't lie)

From: Murray Hogg <>
Date: Sat Mar 21 2009 - 17:53:47 EDT

Hi Glenn,

Just one observation on those Tetlock findings;

Do they in any way account for the manner in which public perceptions are shaped under the influence of expert opinion?

What I'm thinking is that the correspondence between public opinion and expert opinion might--as you suggest--indicate that experts are no better at prediction than non experts. BUT it might also be taken the other way: that the general public are so influenced by expert opinion that they don't, in fact, have an independent view.

The Tetlock studies, in short, might really be measuring little more than the efficiency of popular media in disseminating expert opinion.

By way of analogy; one might poll students in any college class only to discover a remarkable similarity of opinion to their professors. This could be explained by suggesting that college professors are no better educated than their students, but it could also suggest that the student's opinions have been shaped by their professors. And I'm not sure that the Tetlock findings are so very much a different sort of case.

In respects of global warming in particular, I find it hard to imagine that any person expressing an opinion does so in ignorance of expert views on the matter. Consequently, I'm not sure that we have adequate controls on our sample groups here, and therefore not sure whether the Tetlock findings really demonstrate that _uninformed_ opinion is as reliable as that of "experts".

The upshot is that I'm not sure that using the general public as a control group really helps us in determining the accuracy of expert predictions as the views of this control group certainly are not an independent marker. I am, that said, not quite sure what the control group then ought to be.


Murray Hogg
Pastor, East Camberwell Baptist Church, Victoria, Australia
Chairman, Executive Committee, ISCAST Vic <>
Post-Grad Student (MTh), Australian College of Theology
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Received on Sat Mar 21 17:54:19 2009

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