Testing, One,Two, Three

The vast majority of of the human race could not run a 4.7 sec 40 yards downhill, with a twenty-five mile an hour tailwind, but if you are a prospective NFL cornerback or safety a time that fast is way too slow. (Check out, e.g., Mark Zeigler's fascinating San Diego Union-Tribune article). The difference between a 4.4 forty and a 4.7 forty is a bit less than three yards over the distance, which is a lot more than a cornerback can concede to a receiver. The NFL screens several hundred prospective recruits every year, and they are weighed, measured, tested, tested, and tested. That forty yard sprint is likely the most important test, but the NFL also tests how high you can jump, how far you can jump, and how many times you can bench press 225 lbs. And it gives you an IQ test.

That test, the twelve minute, fifty question Wonderlic, is also given to something like 2.5 million other prospective employees every year. The NFL, Walmart, and all the others giving such tests aren't interested in racial theories, whether IQ is hereditary, or whether it truly measures intelligence - or even what intelligence really "is." What they are interested in is whether the prospective employees can read and follow relatively simple written and graphical instructions and complete certain tasks.

Moreover, they aren't deluded into thinking that Wonderlic score is the only determinant of success. The forty yard dash time is crucial for NFL prospects, but it's not the be-all or end-all. If a superhuman player could run the forty in 3.95 seconds he still couldn't play cornerback unless he could also tackle and defend the pass. The Wonderlic, like fancier IQ tests, predicts job performance - not perfectly, only with about a 50% correlation. Consequently, it only predicts about 25% of the variance, often less.

Not especially impressive one might think. However, it is better than any other known test.

Back to football: so how does the NFL do on the test? About the same as job applicants as a whole, 21/50 vs 20/50 for general job applicants throughout the economy. If you check the link, you can see that while the NFL is not exactly brainiac central, the players are no dummies - at least on average.

While quarterbacks are generally considered to have the highest intellectual load in the game - they need to know what all the players are doing on every play - they don't have the highest scores, being narrowly surpassed by offensive tackles and centers. So why are offensive tackles the highest scorers/smartest? (full disclosure - I played offensive tackle in high school - but not well - and am slightly partial to the otherwise unsupported theory that bigger is smarter).

Many of my commenters have beaten me up for thinking that IQ tests are legitimate tools. The legitimate uses (my opinion) don't require that we think IQ is hereditary, or that it unchangeable through life, or that we believe that IQ tests measure "intelligence." It only requires that we believe that the results of such a test can predict performance in some occupation or endeavor. There is plenty of evidence that it does, not perfectly, not actually even very well - just better than any other quick and straightforward diagnostic.

The correlation is not the same for all types of jobs. IQ is most predictive in the lower ranges of the scale for jobs with significant complexity. Persons with IQ scores about 105 perform, on average, rather better on tasks of moderate complexity than those who score about 95. On the same tasks, IQs of 140 are likely little better than IQs of 120 however. Some jobs placements discriminate against those with very high scores, on the grounds that if you are too smart you are too likely to be a smartass, or ask too many questions, or maybe just to get bored and quit.

IQ tests and proxy IQ tests are everywhere in the economy. In addition to all the people who take Wonderlics, there are all sorts of other tests: the SAT, the GRE, the MCAT, the LSAT. If you apply for a professional job you may not get asked to take an IQ test, but that's partly because if you gone to college, they know you have already been through a battery. If you went to a prestigious college, you almost certainly got a very high score on that battery - either that or had a lot of influential alumni connections - so a good deal for the employer either way.