Question
Does IQ predict success?
Short answer
Across large groups, IQ predicts some outcomes moderately well: about 0.51 with job performance, 0.56 with years of education, 0.45 with job level and 0.23 with income. For one person, a single score predicts much less, because many other things, from effort to health to luck, shape a life.
Want your own number? The test is 25 visual puzzles, about 12 minutes, no sign-up.
What the big studies found
| Outcome | Correlation | Source |
|---|---|---|
| Exam results at 16 (from intelligence at 11) | 0.81 | (Deary, Strand, Smith & Fernandes, 2007) |
| Education | about 0.56 | (Strenze, 2007) |
| Job performance | 0.51 | (Schmidt & Hunter, 1998) |
| Occupational level | about 0.45 | (Strenze, 2007) |
| Income | about 0.23 | (Strenze, 2007) |
These are real, replicated findings, and for psychology they are large. The job performance figure comes from a review of 85 years of personnel research (Schmidt & Hunter, 1998). The school figure comes from a sample of about 70,000 children (Deary, Strand, Smith & Fernandes, 2007).
Try one · Abstract Reasoning
Which tile completes the grid?
Tap the option you think is right, or show the answer.
Show the answer
The missing tile has a large hatched circle (option 5).
How to solve it
- Start with the first row and name what changes from tile to tile.
- Every row and every column contains each shape (diamond, circle and square) exactly once.
- Every row and every column contains each fill (hatched, outline and solid) exactly once.
- The size (large) stays the same in every tile.
- Check the rules on the second row, then apply them to the third.
- So the missing tile has a large hatched circle.
That was 1 puzzle. The full test has 25.
What a correlation can and cannot say
A correlation runs from 0 (no relationship) to 1 (a perfect straight line). A value of 0.5 means a clear tendency with a lot of scatter: many people with average scores outperform many with high ones. At 0.23, as with income, the scatter is so wide that knowing someone's IQ tells you very little about what they earn.
Correlations also do not show cause on their own. More schooling can go with higher scores for several reasons at once.
Why group findings do not settle individual cases
Imagine plotting thousands of people, IQ on one axis and job ratings on the other. At a correlation of 0.51 you see a clear upward cloud. Now pick any one IQ value and look straight up: the people at that score are spread across almost the whole range of job ratings. The trend is real, and so is the spread. Both facts hold at the same time.
What this means for you
Your score is one piece of information about one kind of reasoning. It does not measure motivation, knowledge, skill, health, kindness or the choices you make, and none of the research above lets anyone predict an individual life from a number. The guide what IQ predicts, and what it does not goes through each finding in more depth.
Sources
- Schmidt, F. L., & Hunter, J. E. (1998). Psychological Bulletin, 124(2), 262-274. doi.org/10.1037/0033-2909.124.2.262
- Strenze, T. (2007). Intelligence, 35(5), 401-426. doi.org/10.1016/j.intell.2006.09.004
- Deary, I. J., Strand, S., Smith, P., & Fernandes, C. (2007). Intelligence, 35(1), 13-21. doi.org/10.1016/j.intell.2006.02.001