It sounded like an interesting project, but I never got around to it, and have felt guilty about it ever since.
Now there's a paper (found via GNXP.com) on a study of 1066 trainee truckers in the U.S.:
Cognitive Skills Explain Economic Preferences, Strategic Behavior, and Job Attachment, by Stephen V. Burks, Jeffrey P. Carpenter, Lorenz G?¶tte, and Aldo RustichiniThe social scientists gave the trainee truckers the Ravens non-verbal IQ test, an ETS test of numeracy, and had them play a quantitative game called Hit 15. They also had them engage in the kind of Vernon Smith behavioral economics experiments that help measure future orientation and the like.
In large firms of the type we study, the American Trucking Associations consistently report that annual turnover rates exceed 100% (21). Most driver trainees, including our subjects, borrow the cost of training from their new employer, a debt which is forgiven after twelve months of post”training service, but which becomes payable in full upon earlier exit. Yet over half our subjects exit before twelve months, which makes predicting survival of considerable interest.
Figure 4 displays the survival curves for distinct values of a typical socio”economic variable (marital status), as well as for each quintile for the Hit 15 Index. The difference between married and un”married is small, while the difference among the quintiles in any of the cognitive skills scores is large. Marital status is typical of other socio”economic variables, such as credit score, number of dependents, prior job, and so on: these explain little of the variation in survival. The survival curves are similar for the IQ Index and the Numeracy. The difference between survival levels at different scores is particularly large for the Hit 15 Index: the survival for the top scorers is twice as large as for the bottom ones.IQ, numeracy, and the Hit 15 game were all correlated with graduation rates from the one-year training program. The Hit 15 game was a particularly good predictor of who would graduate from the training program. Interestingly, the top quintile in numeracy had a worse graduation rate than the next highest quintile. Perhaps the most numerate tended to get alternative employment as bookkeepers, or whatever, jobs where you get to go home every evening.
Economic analysis has said little about how an individual’s cognitive skills (CS's) are related to the individual’s preferences in different choice domains, such as risk-taking or saving, and how preferences in different domains are related to each other. Using a sample of 1,000 trainee truckers we report three findings. First, we show a strong and significant relationship between an individual’s cognitive skills and preferences, and between the preferences in different choice domains. The latter relationship may be counterintuitive: a patient individual, more inclined to save, is also more willing to take calculated risks. A second finding is that measures of cognitive skill predict social awareness and choices in a sequential Prisoner's Dilemma game. Subjects with higher CS's more accurately forecast others' behavior, and differentiate their behavior depending on the first mover’s choice, returning higher amount for a higher transfer, and lower for a lower one. After controlling for investment motives, subjects with higher CS’s also cooperate more as first movers. A third finding concerns on-the-job choices. Our subjects incur a significant financial debt for their training that is forgiven only after twelve months of service. Yet over half leave within the first year, and cognitive skills are also strong predictors of who exits too early, stronger than any other social, economic and personality measure in our data. These results suggest that cognitive skills affect the economic lives of individuals, by systematically changing preferences and choices in a way that favors the economic success of individuals with higher cognitive skills.