Is there a correlation between self-estimated IQ and measured IQ?

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

Yes. We asked participants the following question: “Out of 100 random people in your country who are of your own age and gender, how many of those 100 people do you think you would do better than on an intelligence test designed to accurately measure I.Q. (if you all took the same test)?” Essentially, this question asks for their IQ percentile. Since IQ is known to be normally distributed, this  question can be directly converted to a self-estimated IQ: the more people think they would outperform, the higher they estimate their IQ to be.

We found a moderate positive correlation between their response to this question and their real, measured IQ (r = 0.23, n = 3688). This means that people are only modestly good at predicting their own IQ.  Here is the scatterplot of this relationship - it is apparent that the line is quite flat which means that both higher IQ and lower IQ people tend to estimate themselves as being closer to the mean than they really are.

What do the other studies say?

Our findings are aligned with meta-analytical estimates of the relationship between self-estimated and measures abilities, with Freund & Kasten (2012) meta-analysis showing a mean correlation of r = 0.33 and Zell & Krizan (2014) meta-analysis showing a mean correlation of r = 0.29 between measured IQ and self-estimated performance.

Takeaways

• Just like in other studies, in our study measured IQ was modestly related to the self-estimated IQ

• Both higher IQ and lower IQ people may have a tendency to estimate themselves closer to the average than they really are.

If you'd like to read the full report, of which this is a section, as one long PDF, you can download it here.

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