I think you do need an answer, because you don’t seem to understand what “success” is. Making money is success, the more the better. Building wealth is success. Getting married and staying married is success. Staying out of jail, staying off of illegal drugs, not having a child out of wedlock, finishing high school, finishing college, finishing grad school, etc., is success. Any positive achievement and/or avoidance of negative outcomes is success in life, and usually it can be measured quantitatively, and these measures of success tend to rise with IQ in an ALMOST linear fashion. The ACT and SAT correlate so strongly with various IQ tests that they serve as pretty good IQ tests themselves.
You are correct, but the tests do not need to be similar. Test scores predict how likely one is to finish college (and how well one will do while there), how likely one is to stay out of jail, how likely one is to have an above-average income, etc. These are all “tests” of life which test scores can predict.
It seems to me that many people just can’t grasp the notions of “on average” or “more likely to.” These words mean exactly what they say. A person with a 32 on the ACT is more likely to finish college than someone with a 27. They are more likely to and on average will have higher incomes. But there is absolutely no way to compare these two people and say with any degree of certainty that the person with the 32 ACT will be more successful than the one with a 27. Factors such as hard work, moral choices, and dedication simply play too large a role. But give me 1,000 random people with a 32 ACT versus 1,000 with a 27, and I will gladly bet the farm that the 32 group will be more successful than the 27 group by almost any measure imaginable.
The greater difference is IQ or test scores, the more likely that the higher IQ person will be more successful. In the overwhelming majority of cases, a person with a 32 on the ACT is going to be more successful by almost every measure than a person with a 12. This ought to be painfully obvious, and I don’t think many people would be willing to challenge this assumption. But if we know and accept that on average people with a 32 on the ACT are substantially more liley (almost certain) to have better life outcomes than those who make a 12, then why is it so hard to grasp that on average a person with a 32 on the ACT is going to have a slightly better chance at success than a person with a 30?
Ultra-liberal Slate featured an essay on IQ and the SAT entitled, “Yes, it really matters.” The link is below:
http://www.slate.com/articles/health_and_science/science/2014/04/what_do_sat_and_iq_tests_measure_general_intelligence_predicts_school_and.html