Bullshit. That is exactly what they did. They applied the same methodology to all of the presidents, which should be evidently ludicrous with the examples I pointed out. My guess is that you have no idea how widely accepted those techniques are, but I know that had I been asked to be a reviewer of the study, I would have had extreme problems with the methods and any conclusions drawn from them.
But I’ll take your hand and walk you through it more clearly. The authors describe the derivation of scores on three measures for all US presidents: Intellectual Brilliance, Openness to Experience, and IQ.
Intellectual Brilliance:
As I said, they used information from biographies, getting estimations from “several” judges about these descriptors. Don’t you see the likelihood of error in a) the original biographical material, which may be quite skewed, erroneous and otherwise unrepresentative, and b) the estimation then of others about how a person unknown to them appeared on three hundred descriptors based on those biographies?
IQ:
Here again, sources of error include: the biographical source material from which to draw the data on “childhood and adolescent achievements,” and the completeness and accuracy thereof, and also the accuracy of the derivation of the average age at which certain achievements would be expected in the general population. Since these authors are referring to another source, the methods for doing so are not made explicit here. There is simply no way, however, to meaningfully translate these types of developmental achievements into “IQ” scores.
Openness to Experience:
This is complete bullshit. The NEO is a measure of personality intended to be completed by self-report, using items that are not necessarily face-evident. There is a good bit of error in ones self-rating on these items. The idea that someone else could complete it about another person and have the ratings mean anything is nonsensical. Furthermore, when someone becomes an expert on a president, there is also a high likelihood of bias, no?
Here are a few examples of items on the NEO specifically pertaining to Openness. Imagine trying to accurately answer these about John Quincy Adams, using a five point rating scale ranging from strongly disagree to strongly agree:
Now imagine that you are an expert on that person, and have come to feel more strongly about him because of your work. Are you likely to endorse items more positively than you would otherwise? Complete rubbish.
The study methods are completely bogus and clearly prone to massive amounts of error. The idea that one could use these methods to determine that George W. Bush has an IQ of 120 (or 60, for that matter) is sheer bullshit.