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Measuring cognitive ability: all scientific details

01 – the scientific foundation

CHC model

The Cattell–Horn–Carroll model joins the Gf–Gc tradition of Cattell and Horn with Carroll’s three-stratum model into a shared taxonomy of cognitive abilities. It orders cognitive performance hierarchically, from a general ability through broader domains such as fluid reasoning, acquired knowledge, quantitative ability or visual processing, down to specific skills. That structure matters for occupational assessment because cognitive performance is not treated as a vague intelligence label, but assigned to a consistent ability model and interpreted in a differentiated way.

McGrew, K. S. (2009): CHC theory and the human cognitive abilities project. Intelligence, 37(1), 1–10.

Foundational publication

Test design

FrameworkCHC model of intelligence
Tasks42
Durationabout 18 minutes
Time limitYes, 60 seconds per task
Task typeExactly one correct answer
Response formatMultiple choice

Measurement quality

ScoringPercentilePercentile 75: better than 75 percent of the Traitwise reference group.
Reference group (norm sample)8,222 peopleWorking population and participants in real selection processes, Germany and internationally; the reference group is growing. A shared norm for the German and English versions.
Criterion validityr = .31Relationship with later performance, Sackett et al. (2022).
ReliabilityCronbach’s alpha = 0.93Very high internal consistency.
Validityg-factor ≥ 70% of test varianceThe test predominantly measures general problem-solving ability.
ObjectivityStandardised administration, automatic scoring

Sources: Traitwise Assessment Framework; Sackett et al. (2022).

02 – Practical example

Excerpts from the live assessment

Recognise logical relationships, combine and exclude. This is not about specialist knowledge. The task shows how confidently someone links information and draws necessary conclusions.

⏱ 00:58Assessment

What follows from the two premises?

1. No rectangle is a circle.
2. All squares are rectangles.

  1. ANo square is a circle.
  2. BAll squares are quadrilaterals.
  3. CNo square is a quadrilateral.
  4. DSome quadrilaterals are rectangles.
⏱ 0:60Assessment

Complete the following sequence:

2, 6, 15, 31, 56, …

  1. A81
  2. B86
  3. C90
  4. D92
  5. E96
⏱ 0:60Assessment

What follows logically from the two statements?

Statement 1:All projects with an international rollout undergo a data-protection review.

Statement 2:Some internal pilot projects do not undergo a data-protection review.

  1. ANo internal pilot project has an international rollout.
  2. BSome internal pilot projects have no international rollout.
  3. CAll projects with a data-protection review have an international rollout.
  4. DSome internal pilot projects have an international rollout.