Data

IQ by profession

Average scores differ by occupation, and the spread within each occupation is wider than the gaps between them. That second fact is the interesting one.

Where the numbers come from

Occupational IQ figures circulate widely and are rarely sourced. Where they do have a source, it is usually one of three things.

Military testing data. Large-scale conscript and enlistment testing, linked to later occupational records. The best of these datasets, because the sample is close to a full population cohort rather than volunteers.

Employment testing records. Aggregated results from cognitive ability tests used in hiring, most famously the Wonderlic, which published occupational norms for decades.

Longitudinal cohort studies. Samples tested in youth and followed into working life.

Each has limits. Military data skews male and young. Employment testing data reflects who applied and was tested, not who holds the job. Cohort studies are decades old by the time the occupational data matures, and the occupations themselves have changed.

The pattern that appears

Across these sources the ordering is consistent, even where the absolute numbers differ.

Occupations requiring lengthy formal education and abstract problem-solving — medicine, law, research science, engineering, university teaching — sit highest on average. Skilled technical and professional work sits above the population mean. Clerical and sales roles sit near it. Manual and service occupations average below it.

The gaps between adjacent occupational categories are generally modest, often smaller than the confidence interval on a single person's score.

Why occupations differ at all

The differences are real and the mechanism is not mysterious. It is selection, operating at several stages.

Educational filtering. Occupations requiring a doctorate have been filtered by every prior academic stage, each of which correlates with cognitive ability. By the time someone qualifies as a physician, they have passed through perhaps six sequential filters.

Direct testing. Some employers test directly. Military occupational assignment uses aptitude batteries explicitly.

Self-selection. People gravitate towards work they find tractable.

Job demands. Roles involving continuous novel problem-solving genuinely favour faster pattern-learning, and the correlation between ability and performance is larger in complex jobs than simple ones.

None of this is a claim that the ordering is deserved or that the filters are fair. Several of them are known to correlate with family background as strongly as with ability.

How these tables get misused

Reading an average as a requirement. An average of 125 in a profession does not mean 125 is needed to do the job. It means the selection process produced that distribution. Plenty of competent practitioners sit well below their occupational mean.

Reversing the arrow. The data shows that people in certain occupations score higher, not that scoring higher causes entry. Education, opportunity and family circumstance all sit in between.

Quoting decades-old figures as current. Occupational norms from the 1970s describe a labour market that no longer exists, tested against norms that have since been superseded. Most tables circulating online do not say when their data was collected.

Ignoring range restriction. Studies of people already in an occupation have, by definition, a restricted range of ability, which artificially lowers observed correlations with performance within that occupation.

What the data is actually good for

Two things, both modest.

It documents that cognitive demands differ across work, which is neither surprising nor controversial, and it quantifies roughly how much.

And it demonstrates the limits of using ability measures for individual selection. When within-group variation exceeds between-group variation, group membership is a poor predictor of individual standing — which is the statistical reason that occupational IQ tables cannot tell you whether you would be good at a job.

If you came to this page wondering whether your score qualifies you for something, the honest answer is that the table cannot tell you. What predicts success in a field is whether you can do the work, and the only way to find that out is to try it.