In a meta-analysis of the relationship between intelligence and socioeconomic success, psychologist Tarmo Strenze surveyed a wide range of research papers dealing with the relationship between these two variables. His study yielded estimates of the correlation between IQ and income that ranged between 0.15 and 0.27. ( Strenze, Tarmo. 2007. “Intelligence and Socioeconomic Success: A Meta-analytic Review of Longitudinal Research”. Intelligence. 35 (5): 415.
This is accessible at: https://emilkirkegaard.dk/en/wp-content/uploads/Intelligence-and-socioeconomic-success-A-meta-analytic-review-of-longitudinal-research.pdf
He reports:
The correlation of [IQ] with income is 0.20 considerably lower [than the correlation with job performance], perhaps even disappointingly low, being about the average of the previous meta-analytic estimates (0.15 by Bowles at al., 2001; and 0.27 by Ng et al., 2005).
A correlation of 0.20 is generally considered weak, meaning that IQ is not closely related to success. In his book Entrepreneurial Genius: The Power of Passion, Dr. Gene Landrum researched the most important behaviours associated with success. At the top of the list is tenacity. If you have a strong desire to succeed in anything and the ability to persevere through adversity, you are much better equipped to succeed in any endeavour than someone of much higher IQ and lower ambition. Many highly successful people, including Albert Einstein and Thomas Edison were dyslexic, so that is not necessarily an impediment to success. Of course, someone of IQ below 100 is not likely to be successful in a career involving mathematics or physics at the highest levels, but most other careers would be within reach of someone with a strong desire and relentless energy.
My personal conclusion drawn from many decades of observation is that success usually comes to those who want it most and are willing to pay the price.
