Types of IQ tests

The five main types at a glance

1. Individual clinical batteries

These are given one to one by a trained examiner. The WAIS-5, for example, is described by Pearson as an individually administered clinical instrument for ages 16 to 90 (Pearson: WAIS-5), and the Stanford-Binet 5 is administered individually from age 2 (PRO-ED: SB5). Pearson's level C tests, which include the WAIS-5, may be bought only by people with a relevant doctorate and assessment training, a state license, or membership in a body such as APA or NASP (Pearson: qualifications policy). They sample several abilities, such as verbal reasoning, visual spatial skills, working memory and processing speed, and combine them into a Full Scale IQ. Fees vary by clinic: one University of Miami clinic lists a comprehensive psychoeducational evaluation at typically 1,750 dollars (Univ. of Miami clinic: fees), and a University of Wisconsin-Madison training clinic lists one at 600 dollars (UW-Madison SPTC: fees).

2. Nonverbal reasoning tests

These tests use figures instead of words. Raven's Progressive Matrices, first published in 1938, are widely used as a measure of fluid, culture-reduced reasoning (Wikipedia: Raven's Progressive Matrices). The Cattell Culture Fair test was designed to measure intelligence with minimal influence from verbal fluency and educational level (Buros: CFIT (store)). The NNAT3 is a group-administered nonverbal test for grades K to 12 (Pearson: NNAT3). They are narrower than a full battery but less dependent on language. See Raven's Progressive Matrices.

3. Group school ability tests

Schools give these to whole classes. CogAT Form 8 measures verbal, quantitative and nonverbal reasoning (Riverside: CogAT Form 8), and its Standard Age Score uses a mean of 100 with SD 16 (Riverside: CogAT score descriptions). The OLSAT 8 covers verbal, nonverbal and quantitative items and reports a School Ability Index (Pearson: OLSAT 8). Both appear on American Mensa's list of qualifying scores, at 132 (American Mensa: qualifying scores).

4. Workplace and military aptitude tests

Hiring tests are short and fast. The CCAT has 50 questions in 15 minutes and reports a raw score and percentile (Criteria: CCAT prep); Wonderlic Select's timed section has 50 questions in 12 minutes (Wonderlic: FAQ). The military's AFQT, drawn from the ASVAB, is a percentile from 1 to 99 (Official ASVAB: scores). These are aptitude tests, not IQ tests; the IQ test vs aptitude test page explains the difference.

5. Unsupervised online tests

Online tests, ours included, are taken without an examiner. American Mensa does not accept unsupervised testing, including electronic or Internet-based tests (American Mensa: qualifying scores). IQ Octopus gives an estimated IQ from 25 visual puzzles, scored with a Rasch model and shown with a confidence range. It is not a clinical or diagnostic instrument, and it cannot be used for Mensa admission, educational placement, disability assessment or employment screening. The online vs clinical comparison covers the trade-offs.

Why scores differ between types

Most modern IQ tests use a mean of 100 and SD 15 (Wikipedia: Intelligence quotient), but older Stanford-Binet forms used SD 16 and the Cattell III scale uses SD 24 (Wikipedia: IQ classification). The same percentile can print as 130, 132 or 148. Convert to a percentile first with the percentile-to-IQ converter before comparing.

IQ Octopus is not affiliated with or endorsed by any test publisher named on this page. Test names are used only to identify and describe the tests. Our free practice tests are not copies of any published test, and no score on IQ Octopus predicts a score on another test.