— IQ test methodology

Cognitive Assessment System (CAS-2): Cognitive Assessment System

Audience

Ages 5-17

Publisher

PRO-ED

What Cognitive Assessment System (CAS-2) measures

Cognitive Assessment System (CAS-2) is a pass-based cognitive assessment for ages 5-17, published by PRO-ED. Like all standardized IQ instruments, scores follow a normal distribution with mean 100 and standard deviation 15 (Wechsler scale), allowing direct percentile interpretation: a score of 115 is the 84th percentile, 130 is the 98th percentile, and so on.

How it works

The test administration depends on its category: scored against published normative tables, with confidence intervals reported alongside point estimates.

Scoring and interpretation

All standardized IQ tests use a normed distribution: the test publisher tested a representative sample of the target population, ranked everyone's raw scores, and assigned percentiles. Your IQ score reflects your percentile within that normed sample — not an absolute measurement.

IQ 130+ = Highly Gifted / Mensa cutoff (top 2%)
IQ 120-129 = Superior (top 9%)
IQ 110-119 = High Average (top 25%)
IQ 90-109 = Average (middle 50%)
IQ 80-89 = Low Average (bottom 25%)
IQ < 70 = Intellectual Disability range (with adaptive functioning assessment)

Take an IQ test that mirrors clinical methodology

Core Brain uses IRT 3PL Bayesian scoring — the same family of methods as the WAIS and Stanford-Binet — in a 20-minute online format.

Strengths and limitations of Cognitive Assessment System (CAS-2)

Strengths: Standardized, normed, and validated for the intended population.

Limitations: Susceptible to test-taking strategy effects, anxiety, time-of-day, and motivation. Standard error typically ±5 points.

Frequently asked

Who administers Cognitive Assessment System (CAS-2)?

Trained administrators in the relevant setting (school, employer, military, etc.). Some forms can be self-administered for self-knowledge purposes.

Is Cognitive Assessment System (CAS-2) accepted by Mensa?

Mensa accepts a list of approved supervised tests. Check Mensa International's current accepted tests list; many Wechsler and Stanford-Binet results qualify.

How does Cognitive Assessment System (CAS-2) compare to online tests?

Online IQ tests like Core Brain use the same statistical framework (deviation IQ, mean 100 SD 15) and most are calibrated against normed distributions. They are not clinically diagnostic but approximate professionally administered tests reasonably well for healthy adults.