Cognitive Assessment System (CAS2) Scores Explained: PASS Scales

The Cognitive Assessment System, Second Edition (CAS2) is an individual intelligence test for children and teenagers aged 5-0 to 18-11. It was written by Jack Naglieri, J. P. Das and Sam Goldstein and published in 2014. Its scores are standard scores with a mean of 100 and a standard deviation of 15, the same scale as the Wechsler tests, so a 115 is about the 84th percentile. What differs is the structure: four PASS scales instead of five Wechsler indexes.

Below: what PASS stands for, the subtests, how to read a CAS2 score as a percentile, what changes at age 8, who may give the test, and how it differs from the Wechsler tests.

What does the Cognitive Assessment System (CAS2) measure?

Four mental processes, called PASS: Planning, Attention, Simultaneous and Successive. The publisher describes it as based on "the cognitive/neuropsychological theory called PASS". Stoelting, a test distributor, gives short definitions of each process:

• Planning: "a cognitive process requiring the individual to determine, select, and use a strategy to solve a problem."
• Attention: "a cognitive process requiring the individual to selectively attend to a particular stimulus".
• Simultaneous: "a cognitive process involving integrating separate stimuli into a single whole or group."
• Successive: "a cognitive process requiring the serial ordering of things."

In plain words, Planning is choosing a way to solve a problem. Attention is focusing on one thing and ignoring another. Simultaneous is seeing how parts fit into a whole. Successive is keeping things in the right order, such as a string of words.

What are the CAS2 subtests?

The extended battery has three subtests in each PASS scale, which makes 12. The core battery has two from each scale. The publisher lists the extended battery like this:

• Planning: Planned Codes, Planned Connections and Planned Number Matching
• Attention: Expressive Attention, Number Detection and Receptive Attention
• Simultaneous: Matrices, Verbal-Spatial Relations and Figure Memory
• Successive: Word Series, Sentence Repetition (ages 5-7) or Sentence Questions (ages 8-18), and Visual Digit Span

Two vendor pages say there are "four" Successive subtests but name only three, because the middle one is a single slot that changes with age. We could not find a public list of which eight subtests form the core battery, so check your own report.

A shorter test, the CAS2: Brief, uses four subtests: Planned Codes, Simultaneous Matrices, Expressive Attention and Successive Digits, according to its UK distributor. There is also a teacher-completed Rating Scale for ages 4 to 18, a Spanish supplement kit and a fully digital format.

How do you read a CAS2 score?

Read it as a standard score on the usual IQ scale. CAS2 scores follow one rule: the CAS2's makers state that it yields a standard score "with a mean of 100 and a standard deviation of 15". One standard deviation is 15 points, so most children score between 85 and 115.

The table turns standard scores into percentiles with normal-curve arithmetic. The publisher's own tables are the final word, and they can differ by a fraction of a point:

• 70: 2.3rd percentile (two standard deviations below average)
• 80: 9.1st
• 85: 15.9th
• 90: 25.2nd
• 100: 50th
• 110: 74.8th
• 115: 84.1st
• 120: 90.9th
• 130: 97.7th

The CAS2's publishers do not print their score labels, such as "Average" or "Superior", on any public page we could find. The labels and their ranges sit in the test's handbook and the scoring report. Our guides to DAS-II scores and Stanford-Binet 5 scores show how other publishers label the same scale. Put any score into the IQ percentile calculator to see its position on the bell curve.

What changes at age 8?

One subtest. The Successive scale uses Sentence Repetition for ages 5 to 7 and Sentence Questions for ages 8 to 18. So a child tested at 7 and again at 9 is not doing the same task on that scale.

The publisher pages do not say how this affects comparisons over time, so we do not say it either. What it means in practice is that a change in the Successive score between those two tests mixes a change in the child with a change in the task. Ask the psychologist who gave the test how they handled it.

How is the CAS2 different from the Wechsler tests?

Mainly in structure. The WISC-V reports five primary indexes, as our guide to WISC-V index scores explains, while the CAS2 reports four PASS scales and a Full Scale. Both use the 100 and 15 ruler.

The makers also describe the CAS2 as based on a theory of how the brain processes information, not on a list of school-like skills. We found no independent review of this second edition, so we cannot say whether PASS describes children better than other models. The first edition's structure was debated in the research literature, and our piece on full-scale IQ and index scores explains why a profile can differ from the total.

Anyone choosing between tests should know that no single battery is "the" intelligence test. Our guide to how IQ tests work covers what they share.

Who can give the CAS2, and how long does it take?

Only trained professionals. Vendors label the qualification level differently: Pro-Ed and PAR list level C, MHS lists level B, and Hogrefe UK lists "Level 2", because each vendor uses its own scale. Testing takes 40 to 60 minutes, and PAR adds 5 to 10 minutes for scoring.

The CAS2 was standardized on 1,342 children and adolescents. MHS says the group was "closely representative of the population of the U.S. based on census data". The census year and the exact matching variables are not on the vendor pages we read.

Because a child's result depends on the test and the day, a single CAS2 score is a range, not a point. The same goes for the test on our IQ Metrics site, which is not a clinical assessment.

Take the IQ Metrics test and read the result against the bell curve in our IQ bell curve guide. A school or clinic assessment such as the CAS2 is a separate, professionally administered test.

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