What Is the ERB Test? The CTP Explained

The ERB test, formally known as the CTP (Comprehensive Testing Program), is a standardized achievement battery that independent and private schools give to students in grades 1 through 11. It measures how well students have learned reading, writing, mathematics, and other academic content, and from grade 3 onward it adds verbal and quantitative reasoning sections that resemble ability testing more than classroom achievement. The test comes from ERB, the Educational Records Bureau, a nonprofit assessment organization that merged with the Enrollment Management Association in March 2026 to form a new organization called E3n. This article explains what the ERB test covers, how independent schools use it, how its scores are reported, and how it differs from a true IQ test.

Parents often hear "the ERBs" used loosely, so it helps to be precise. ERB is the organization; the annual achievement test most families mean is the CTP. According to the publisher, the CTP is "a summative assessment of learning achievement" whose purpose is to identify the academic strengths and weaknesses of individual students and groups of students so schools can make informed decisions about their curriculum. ERB describes it as the primary achievement assessment used by independent schools around the world, backed by more than 95 years of test-development experience.

The test is administered once a year, in either a fall or spring testing window, in paper or online formats. Schools choose which subtests to give, so two students at different schools may sit for different combinations of sections. Editions of the test are numbered (CTP 4, CTP 5, and so on); the most recent numbered edition is the CTP 5, though ERB's current materials mostly refer to the assessment simply as the CTP.

The organizational picture changed recently. ERB and the Enrollment Management Association, the nonprofit behind the SSAT admission test, completed a legal merger on March 2, 2026, creating a combined organization named E3n. The publisher states that the merger brings together "nearly 170 years of combined expertise in enrollment and achievement." For families, the tests themselves continue under their familiar names, including the CTP and the ISEE admission test, and ERB's school-facing materials now point members to an E3n portal.

The CTP is built from separate subtests, each tied to a grade range. According to the publisher's current subtest list, the battery includes:

• Reading comprehension (grades 1-11): understanding passages, drawing inferences, and interpreting what an author is doing.

• Mathematics (grades 1-11): grade-level math content aligned with what students are expected to have learned.

• Early literacy subtests: word analysis in grades 1-2 and auditory comprehension in grades 1-3, which check decoding and listening skills in the youngest testers.

• Writing mechanics (grades 2-11) and writing concepts and skills (grades 3-11): grammar, usage, punctuation, and the ability to recognize effective writing.

• Verbal reasoning and quantitative reasoning (grades 3-11): the two sections that measure reasoning with words and numbers rather than taught content, described in the next section.

• Vocabulary (grades 4-11): breadth and depth of word knowledge.

• Science (grades 3-9, online only) and Algebra I (grades 7-9): optional content subtests some schools add.

Because schools pick and choose, a third grader might take five or six subtests while a ninth grader takes a different set. There is no single fixed "ERB test" experience across schools.

The most interesting design feature of the CTP, from an intelligence-research perspective, is that it deliberately separates achievement from reasoning. ERB states that starting in grade 3, "separate CTP reasoning and achievement subtests provide greater insight into each student's academic growth, assessing attained knowledge alongside reasoning."

The verbal reasoning section asks students to work with word relationships, category membership (which word fits or does not fit a group), and "deductive reasoning" and "inductive reasoning," meaning drawing necessary conclusions from given statements and inferring general patterns from examples. The quantitative reasoning section covers numerical, geometric, and measurement comparisons, extending patterns, interpreting symbolic representations, and evaluating statistical arguments. These item types depend far less on any particular curriculum than a mathematics or vocabulary subtest does.

That puts the CTP's reasoning sections in the same family as school ability measures such as the CogAT, which we profile in what is the CogAT test. Reasoning tests of this kind correlate substantially with scores on full intelligence tests because they tap the same underlying general reasoning ability. A student who scores much higher on the reasoning subtests than on the achievement subtests may not yet be showing what they are capable of in the classroom, while the reverse pattern can indicate a student working very hard to compensate. Teachers and learning specialists at independent schools routinely look at exactly this contrast.

The comparison is worth taking seriously but not overreading. Two subtests administered in a group setting are a coarse measure, and a single discrepancy between scores can reflect ordinary measurement error rather than a meaningful gap.

The CTP is a "norm-referenced" test, meaning a student's score is interpreted by comparison to a defined group of other test takers rather than against a fixed passing standard. This is where ERB reporting differs most from state public-school testing, and it is the single most important thing for parents to understand when reading a score report.

According to the publisher's parent guide, CTP reports can compare a student against several distinct norm groups:

• National norm (NN): a representative sample of all U.S. students at that grade level.

• Independent norm (IN): students at independent schools who took the CTP at the same time of year over the past three years.

• Suburban norm (SN): students at suburban public schools who took the CTP in the same window.

• Association norm: students at schools belonging to the same independent-school association as your child's school.

Because independent-school students are, on average, a high-scoring group, the same performance yields a noticeably lower percentile against independent norms than against national norms. ERB is explicit about this: a student's percentile "is usually lower when compared to a stronger norm group and higher when compared to a weaker norm group." A child in the 85th percentile nationally might land near the 60th percentile against independent norms, and neither number is wrong; they answer different questions. ERB maintains these comparison groups as "rolling norms" built from roughly three years of accumulated data, refreshed annually. Public-school achievement batteries such as the Iowa Assessments work on the same norm-referenced logic, which we cover in what is the Iowa test.

Schools use the results in several ways: tracking individual growth from year to year, spotting curriculum-wide weaknesses when a whole grade dips on a content strand, and flagging students for extra support or enrichment. ERB has also published an analysis of more than 1,300 students showing that CTP scores in grades 8 and 9 correlate strongly (the publisher reports correlations well above .50) with later PSAT, SAT, and ACT performance, with quantitative reasoning among the strongest predictors. Some schools use CTP results in this way as an early college-readiness signal.

A CTP score report presents the same performance through three related metrics, each defined in the publisher's parent guide:

• Scale scores: scores based on both the number of questions answered correctly and the difficulty of those questions, useful for tracking growth across years.

• Percentile ranks: the percentage of students in the norm group who scored the same or lower. A 70th percentile means the student outperformed 70 percent of the comparison group, and it does not mean the student answered 70 percent of items correctly. For a fuller treatment of this metric, see IQ percentiles explained.

• Stanines: a 1-to-9 scale ("stanine" is short for "standard nine") that divides the norm group into nine bands. Stanines 4 through 6 represent average performance and capture over half of all students; 7 through 9 are above average; 1 through 3 are below average. Stanines are deliberately coarse, and ERB itself notes they "are not the most precise measure of a student's ability."

Reports also show a "probable range" around each percentile, an error band estimating how the score might vary with a different set of questions. ERB advises that two subtest scores whose probable ranges overlap should not be treated as meaningfully different. That is sound psychometric practice, and it is a caution worth applying to every standardized score a child receives.

No. The CTP is an achievement battery. Most of its subtests measure knowledge and skills that were directly taught, which is precisely what an IQ test tries not to do. An intelligence test samples reasoning across many domains while minimizing dependence on specific schooling; an achievement test does the opposite by design. The CTP's verbal and quantitative reasoning sections sit closest to the IQ side of that line, and they are genuinely informative about reasoning ability, but two group-administered subtests do not produce an IQ score, and ERB does not report one.

The CTP also stops at grade 11 and exists only for students at participating schools. Adults who took "the ERBs" as children sometimes want a current, properly normed measure of their reasoning ability. For that purpose, an option is the RIOT IQ test (Reasoning and Intelligence Online Test), developed by RIOT IQ with psychometrician Dr. Russell T. Warne for adults 18 and older. It includes 15 subtests across six cognitive indices (verbal reasoning, fluid reasoning, spatial ability, working memory, processing speed, and reaction time), takes about 52 minutes, and reports scores on the familiar mean-100, standard-deviation-15 IQ scale. Like any online measure, it does not replace an individually administered diagnostic evaluation when one is clinically needed. You can take the RIOT IQ test at riotiq.com.

The CTP spans grades 1 through 11, according to ERB. Which subtests a student takes depends on grade level and on the school's choices; the reasoning sections begin in grade 3.

No. Both come from ERB, but the ISEE is an admission test taken once when applying to an independent school, while the CTP is an annual achievement assessment given to enrolled students.

There is no passing score. Against independent-school norms, stanines 4 through 6 (roughly the 23rd to 76th percentile) represent average performance among a high-achieving comparison group. The same performance would usually look stronger against national norms.

Most likely the norm group changed. ERB reports scores against independent-school norms, a stronger comparison group than the national samples used by most public-school tests, so percentiles typically come out lower.

Familiarity with the format helps reduce anxiety, and ERB now offers practice through a Kahoot! partnership. Heavy coaching mostly distorts what the test is for, which is giving the school an accurate picture of learning.

Yes. ERB and the Enrollment Management Association completed their merger on March 2, 2026, forming E3n, and the CTP continues to be offered to member schools.

1. ERB. (2026). CTP by ERB: Summative assessment for grades 1-11. Educational Records Bureau. erblearn.org

2. ERB. (2019). Parent guide: Individual narrative report (Comprehensive Testing Program). Educational Records Bureau. cdn.erblearn.org

3. ERB. (2026). Merger news: EMA and ERB officially create E3n. Educational Records Bureau. erblearn.org

4. ERB. (2025). The CTP test: Our early indicator for college entrance exams. Educational Records Bureau. erblearn.org

5. ERB. (2024). Spring 2024 CTP norms updates. Educational Records Bureau. erblearn.org

Hero photo: an open book on a stack of books beside a fresh apple on a bright desk. Photo by Shixart1985, CC BY 2.0 (https://creativecommons.org/licenses/by/2.0), via Wikimedia Commons; cropped from the original.