Most IQ tests are multiple guess and have little or nothing to do with somebody's knowledge or of their ability to sort things out.
I don't know about SAT tests today, but when I was in school 40 years ago they were also multiple guess, and about as indicative of somebody's knowledge as a fish's ability to climb trees.
The best way to determine the cause of accidents- aside from investigating them- is to talk to peer groups of the study subject. In this case I have seen several full and part time farmers tune in, yet what they said doesn't support what the thesis wants to believe.