Is IQ positively related to income?

Note: This is a section of a longer article. To go to the start, click here.

To a small degree, yes - we found that higher IQ people had higher incomes, but only slightly. We collected two types of income: personal income (of each individual) and a household income. The correlation between IQ and self-reported personal income in our study was r = 0.07, while the correlation between IQ and self-reported household income was twice as strong: r = 0.15 (n = 3688 for both). Both of these correlations are quite low, but in a nutshell, they mean that as the IQ rises, the income rises too, albeit to a small degree. It's interesting that we found a greater correlation with household income than personal income, because it's easier to see how IQ might directly cause more personal income than to see how it could cause household income (that's not due to personal income) to rise - this suggests that the link between IQ and income is more complicated than higher IQs simply causing individuals to earn more. Here are the scatterplots showing the relationships between personal/household income and IQ. Each study participant is shown as a black dot, and the blue line shows the trendline.

What do the other studies say?

Our estimate is generally in line with previous studies on the relationship between IQ and income, although the effect sizes we obtained are somewhat lower than what has previously been found in the literature. For example, a meta-analysis by Ng et al. (2005) analyzed eight different data sets and reported a correlation between cognitive ability and salary of r = 0.27. Somewhat more inclusive meta-analysis by Strenze (2007) estimated a correlation between IQ and income at r = 0.22 based on the analysis of 20 data sets. We are unsure why our study found a lower correlation, but it may be that our samples were more restricted in income (i.e., had a narrow range) than some other samples.

Takeaway

• Higher IQ is linked to greater income but the link isn't very strong. Part of this effect may be that higher IQ people can get hired and perform better at some high paid jobs. There are also other plausible explanations for why the effect is weak such as that other abilities are more important in work or that income depends more on the field of work rather than on the cognitive abilities. However, this is beyond the scope of this report.

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