CogAT to IQ

Posted by: Aden

CogAT to IQ - 07/30/18 12:46 PM


I am a 16-year-old student. A year and a half ago, I was fishing around for my old report cards when I found a report for a CogAT test that I did back in the third grade in February of 2011.

Here are my scores:

Verbal: 118
Raw: 57/65
Stanine: 7
Percentile: 87

Quantitative: 121
Raw: 54/60
Stanine: 8
Percentile: 91

Nonverbal: 123
Raw: 59/65
Stanine: 8
Percentile: 92

Composite: 124
Percentile: 93

Profile: 8A

These scores were below the gifted program's requirements, which requested that either the composite score be above the 97th percentile, or 2 or more subtests be above the 98th percentile. However, that's not my main concern.

While I have no issue with these scores, I have heard that a CogAT can give one a ballpark IQ score if the subtest scores are relatively at the same level, which in my case (as I have a relatively even CogAT profile) seem legitimate. However, at the same time, I have also heard that the CogAT only tests "learned abilities" whereas IQ tests look for innate abilities. Therefore, a CogAT score cannot give an accurate estimate of an IQ score.

I ask this as I have been addicted to these notions for about a year and a half (addictively searching about high IQ and CogAT and correlations) and I want to provide myself with some closure. Taking into account the sides of the argument that I mentioned earlier in the post, my question is: Can an IQ score be lower than a CogAT score (i.e. CogAT 124 and IQ in the average range), or are both usually at the same level (IQ and CogAT both 124) if an even profile is achieved?

Posted by: ajinlove

Re: CogAT to IQ - 08/02/18 08:35 AM

Posted by: aeh

Re: CogAT to IQ - 08/02/18 09:46 AM


Frustratingly, the answer is all of the above. The CogAT can be higher, lower, or comparable to an individually-administered IQ measure. It is usually somewhere in the same vicinity, but not necessarily. I wouldn't use it to estimate an IQ.

But regardless of the "true" IQ score, you appear to be a bright, capable, and articulate young person. I hope you are finding your educational and personal development needs met these days, whether in or out of school.
Posted by: Aden

Re: CogAT to IQ - 08/16/18 07:45 PM

Thank you so much for your answers! I do not remember whether I was bored or not in elementary school (don't remember any of it at all, to be honest) and in addition the district only tested students once. I think that the gifted program was useless in my school as it seemed that all the students did were art projects. However, I will probably take an IQ test once I am a bit older.
Just one more question, if it permits. A PSAT score can be derived from an SAT score, and I have heard that SAT scores administered to 7th graders in talent searches can be used to derive IQ scores (read about it in a post somewhere). Is this plausible? It has also been said that talent searches are used to differentiate among students in the top 5% of standardized tests. Knowing this information, is it possible to predict IQ from a PSAT score?

Regards again.


(In the link, it is the first answer).
Posted by: aeh

Re: CogAT to IQ - 08/17/18 02:34 PM

I'll apologize for not checking my sources before responding...but my recollection is that it was possible to estimate IQ from SAT scores back before the reentering decades ago (I think in the late 80s?), but since then, changes in the population that takes the SAT (more diverse, which is good, but less homogenous, which makes it less comparable to past research, and less selective, which lowers the meaningful ceiling), and thus the norms, and changes in the nature of the test, away from more reasoning, and toward more achievement, have flattened its usefulness for estimating IQ. IOW, it no longer spreads the cognitive upper end of the population as well as it did a generation ago.

It is still possible to make some estimates based on 7th grade SAT scores, but it is just that, a rough estimate.

The PSAT is a different question. The most recent PSAT and SAT are on the same scale, which makes them a little easier to convert, but the old PSAT was not quite as comparable. Did you take the new PSAT, or the old one? You can also just use your direct percentile, if you took it at typical age (I assume you took it this past school year). That's a much simpler way of estimating ability from achievement, although it's still just that--an estimate.

I looked at that quora answer: that is certainly a plausible approach to estimating IQ. I do know, though, anecdotally, that it doesn't necessarily provide much precision, since my personal data set of multiple related persons has simple differences of 10-50 points between SAT-generated estimates and individually-administered assessments, in both directions. And again, much of the data Lubinski, et al used was from prior versions of the SAT. I would say, though, that if a person is at or above the 50th %ile in the data set, that is a pretty good indication that that person has high cognitive gifts, since the pre-qualifying criteria for participating usually include previous assessment data in the 95th %ile or above (about 125 on tests like the CogAT).
Posted by: Aden

Re: CogAT to IQ - 08/17/18 03:02 PM

I took the PSAT 8/9 as an eighth grader in October of 2015, the PSAT/NMSQT in ninth grade in Fall 2016, and the PSAT/NMSQT in tenth grade as a tenth grader last year. I use the 8/9 mainly because it was the test that I took without any preparation whatsoever. Yes, I know that SAT scores post-1995 correlate weakly with IQ tests, which is why I didn't use my more recent scores for estimation. Could my earliest score (PSAT 8/9) be directly converted to an SAT score?

In regards to the study by Lubinski, are you saying that his research might be outdated for current versions of the SAT for talent searches?
Posted by: Emigee

Re: CogAT to IQ - 08/17/18 03:20 PM

This thread is such a coincidence, as just a few days ago I learned that high IQ societies such as Mensa and Triple 9 accept SAT and GRE scores (from earlier years only) as qualifying scores. I had been reading a Slate article that defended the use of SATs in college admissions, fell down a Google rabbit hole, and found myself reading about this. I hadn't even heard of Triple 9 before. Anyway, I thought it sounded kind of nuts to use these achievement tests as proxies for IQ, especially when I realized that I would qualify for both societies (Mensa easily according to both tests, Triple 9 according to GRE scores, barely). In your professional opinion, aeh, do you think this approximation is justified? I have no skin in this game, as I have no interest in joining such a society, but I was a little startled as I have never had an actual IQ test and never would have pegged my own abilities that high. My DH would qualify for both as well, so that may explain a bit about our son...well, to some extent (his brain seems capable of feats that neither of us can quite understand).
Posted by: aeh

Re: CogAT to IQ - 08/17/18 05:21 PM

emigee, I've had the same thought about Triple Nine. Mensa has relatively low standards, so that one doesn't surprise me as much. The rationale, I believe, is two-fold: 1, the population that took these tests in those eras was pre-selected for the upper few percent, so the tests effectively spread out the right-hand tail enough to discriminate scores above +2 SD; and 2, the earlier tests were more aimed at "aptitude", meaning reasoning ability or learning potential, which better approximates the same qualities assessed by IQ tests.

The first assumption has changed in recent decades, since the push for college for all (SATs and ACTs), which has since morphed into post-graduate for all (GREs). Some states even use the SATs as a state-mandated high school exit exam (much to the delight of the College Board), which means that every single high school student is expected to take them, a far cry from the data pool up through the early 80s, which was a relatively stable top 10-15% of the educational population (sadly, with no allowances made, of course, for economically, socially, or instructionally disadvantaged populations with no access to the test or its preparations).

The second assumption has changed as the test has become more focused on acquired skills, partly, I suspect, in response to the movement away from liberal arts, and toward school-to-work in education.
Posted by: Aden

Re: CogAT to IQ - 08/17/18 08:56 PM

I have also heard that Triple Nine Society still accepts ACT scores of 34 or higher for their society. Why is that so, if the ACT is an achievement test?
Posted by: aeh

Re: CogAT to IQ - 08/21/18 05:37 PM

Yes, Lubinski & Benbow did that research on the old SAT, so those estimate formulas do not apply to recent SATs.

As to the ACT scores for the Triple Nine Society: that is a private organization; I cannot speak with any certainty to why they continue to accept the ACT. I assume their psychometric consultants have some data that support this decision. My speculation would be that the fact that the ACT has not changed significantly in decades helps them to have some standard of comparison. It's also the case that achievement tests do have some correlation to intelligence (overachievement is not hypothetically possible, after all), and a composite score of 34 is a pretty low percentage occurrence. Based on the published tables, it appears the population mean in the standardization sample was a score of about 16, with a SD of about 6, and +3SD thus falling at 34, corresponding to the 99.9th %ile. Note that DYS also allows certain achievement tests to be used as proxies for cognitive ability.

The current SAT is less usable for this purpose, when given to typical-age students, because the 99th %ile is about 780, which doesn't leave much headroom to spread that last percentile. It still has some utility for above-grade-level testing, which is why the major talent searches still use it, but since they keep changing the test, it becomes more difficult to do longitudinal research and comparisons. (Also see the comments I made in my previous post.)

More straightforward method of estimating your rank in the population (not your IQ):
Here's the percentile table for the PSAT 8/9 the year you first took it:
The national 50th %ile for total score is 820, with a SD of about 155, which puts the 99.9th %ile at about 1285.

I hope this satisfies your curiosity, at least a little bit.
Posted by: Aden

Re: CogAT to IQ - 08/21/18 07:50 PM

Thank you for providing this! I never was able to find this information! Although looking at this report, my percentile (user-based) is different than the score I achieved shown here. For example, I scored 1110 on the PSAT, which on my report places me in the 95th percentile, yet this report for Spring 2016 reports me at the 97th percentile (all percentiles user-based). Why would that be?

Also, I have heard of ways to convert new SAT scores to pre-1995 SAT scores. Would that be a reliable way to do so? If so, how would that be done?

Finally, regarding your stance on the ACT; it kind of makes sense now, since the average that the ACT board reports (which is 20.8 approximately) would represent the average of people who took the ACT, and not the general population, which IQ tests usually do. Would that be correct?
Posted by: Aden

Re: CogAT to IQ - 08/21/18 08:33 PM

The reason that I asked about the ACT and Triple Nine is because I thought that it was overestimating my correlated IQ score based on my first time SAT practice test score with no prep converted to an ACT score (I know that it's not accurate in the slightest, but it's the best that I could do).

Here is how I correlated the scores:

When I estimated the IQ score, it put me above 130, and I know for certain that the estimated score was way too high for me. So another question is, is this above chart accurate?
Posted by: aeh

Re: CogAT to IQ - 08/22/18 11:55 AM

I think you're better off using the actual PSAT percentile charts to estimate your IQ. Once you have the percentile, you can go to any percentile-to-IQ conversion chart and find a number. The chart you linked is accurate as far as it goes, but doesn't include any of the measures you actually have taken. Practice test scores aren't particularly reliable (a lot of people have fairly different scores on test day).

For the PSAT percentile chart, make sure you are comparing yourself to the correct grade level (I made an assumption about your grade level at time of testing, which may or may not have been accurate), and to the national norms, not the user norms. The user norms are a slightly more selective population than the national norms. Oh, also these percentiles are for the spring 2016 test, which apparently was slightly less selective than the fall 2015 test for which you sat. But the national norms are the ones you want, anyway.

On the ACT: yes. As with the user vs national norms of the PSAT, the user norms are more selective.

And FYI, the 97th %ile on most cognitive assessments is about 128.
Posted by: Aden

Re: CogAT to IQ - 08/22/18 12:17 PM

So what you are saying is that a PSAT percentile should be about the same as an IQ percentile?

The reason I ask is because I took the NMSQT in Fall 2016, and I received a score of 1250 on it. Since the test score can be converted to the PSAT 8/9, I would be receiving a 98th percentile score (national) if I had taken it as a 9th grader. This score is Mensa eligible, while the former one you mentioned (97th or 128) isn't.
Posted by: aeh

Re: CogAT to IQ - 08/22/18 01:16 PM

Roughly. They're not the same test, obviously, but both indicate your rank order in the population in related skills. As much as the College Board claims you can directly equate all of their measures, I would be careful about doing so to that level of precision. 97th and 98th percentile aren't substantially different (despite one falling one side of the Mensa line, and the other falling on the other side). On the actual PSAT/NMSQT percentile chart from your 9th grade administration, you fall at the 95th %ile for 10th graders (, which I cite mainly to point out that a point up or down here and there can appear to make a difference, but really isn't meaningful.

You have NMSQT scores from fall 2017, when you were actually a 10th grader, and thus the 10th grade national percentile charts from the PSAT/NMSQT would apply to you. That would be a better way of ordering you than extrapolating onto the PSAT 8/9 charts from your 9th grade PSAT/NMSQT score.

The bottom line, again, is that you are clearly bright and capable, and on an excellent track to be college-ready academically. Your life outcomes are highly unlikely to be affected principally by whether your "true" IQ falls to one side or the other of the nominal GT line, since ultimately, noncognitive factors (character, responsibility, work ethic, resilience to failure, compassion, social skills, etc.) will distinguish you more from other high achievers --GT-identified or otherwise-- than intellect alone.

A kind-hearted and trustworthy 128 IQ is far to be preferred over a self-centered, cruel --or even merely careless-- 148.
Posted by: Aden

Re: CogAT to IQ - 08/22/18 01:41 PM

I definitely do not think that 128 is low as an IQ score. (actually doubted that score at first, thinking it may be too high). However, you are right. It is much better to have a steadfast personality than having one that constantly changes for the good or the bad. Besides, after 120 one can accomplish pretty much anything!
Posted by: Aden

Re: CogAT to IQ - 08/22/18 01:49 PM

I'm sorry for all these incessant questions, but I may have a few more that I may not remember. Here is one I have, though. If I were to take a WAIS test and scored 128 FSIQ, what are some possible subtest profiles that could occur? (as in with VCI, PRI, WMI, and PSI scaled scores with the subtests scaled scores, like with Coding, Similarities, etc.?) Could you show some possibilities of such profiles? I want to see some examples just to understand how scoring works. Once again, sorry for all these incessant questions.
Posted by: aeh

Re: CogAT to IQ - 08/22/18 03:35 PM

No need to apologize, Aden! I'm happy to help you understand how this all works.

There are quite a number of possible WAIS-IV profiles that could result in FSIQ 128. You could have an even profile, with a lot of strong 13s, 14s, and 15s among your subtest scores, or a spiky one, with some essentially average scores (10s, 11s, 12s) and some very high scores (17s, 18s, 19s). You might even have some extreme strengths paired with significant weaknesses. The subtests comprising your index scores could be split in a similar way, or they could be more consistent within indices. If you have marked learning preferences, some of the indices might be higher than others.

The way scoring works for the index scores (VCI, PRI, WMI, PSI) and the composite scores (FSIQ, GAI) is that subtest scaled scores are added, and then the sum of scaled scores is converted to a standard score. The conversion doesn't take into account how you obtain that sum of scaled scores. So, for instance, if the sum of scaled scores = 138 converts to an FSIQ = 128 (don't take this as the real numbers, as I don't have the tables in front of me at the moment), there will be no distinction between obtaining this from 8 14s and 2 13s (mostly Superior with a couple of High Average) vs 6 19s (Very Superior, at the top of the scale) and 4 6s (below average). Functionally, of course, you might expect pretty noticeable differences between someone who is uniformly a bit stronger than average across the board, and someone who has exceptional strengths in the upper extreme of the population, but also has deficiencies in certain areas (the latter individual is likely to be twice exceptional--having both extreme gifts and some kind of learning disability).

Subtest scaled scores are based on conversions from raw scores (the actual number of points obtained on the task) to scaled scores using age norms. On the WAIS, the age norms are slightly less critical than on the WISC, but they do still matter. At age 16, you would be compared to other 16-17 year-olds, while, say, your 32-year-old physics teacher would be compared to other 30-39 year-olds. If you wanted to compare you to each other, based on your actual performance at this moment in time, you could convert both scores using the reference norms. This would compare your absolute performance, rather than your rank order among your age peers.
Posted by: Aden

Re: CogAT to IQ - 08/22/18 04:53 PM

And if there are major discrepancies in scores (i.e. some 10s and some 19s), that might suggest a learning disability of some sort? Also, how would the GAI be calculated if there is hypothetically the aforementioned discrepancy, since both the FSIQ and GAI can differ?

Also, do certain subtests have more weight to them than others, similar to class tests that have 65% the weight of your final grade?
Posted by: aeh

Re: CogAT to IQ - 08/23/18 08:42 AM

Yes, it is possible that large discrepancies in the subtest scores might suggest interfering factors, such as learning disabilities.

The GAI is calculated the same way as the FSIQ; it just doesn't include the WMI and PSI subtests.

The WAIS-IV composite scores are unweighted. There are other tests that are weighted, such as the Woodcock-Johnson (WJIV, currently).
Posted by: Aden

Re: CogAT to IQ - 08/23/18 10:04 AM

And how are raw scores (for both subtests, FSIQ, and GAI) converted into scaled scores?
Posted by: aeh

Re: CogAT to IQ - 08/23/18 11:02 AM

Raw scores are converted into scaled scores using the age-based norm tables. Some cognitive skills have known population profiles vs age (e.g., working memory and fluid reasoning reach peaks in the early 20s), so finding an individual's standing among age-peers requires using age norms. Raw scores apply only to scaled scores for subtests.

Index scores (FSIQ, GAI, VCI, PRI, WMI, PSI) are determined by taking the sum of the relevant subtest scaled scores and converting them to standard scores using the composite score tables, which are not additionally age-normed. (All ages use the same conversion charts.)

For example, say you get a raw score of 9 (meaning you received credit for the first nine items on the task) on Arithmetic (again, none of these are real numbers, as I don't have the tables in front of me). You go to the age-norm tables, and find that, at your age, that converts to a scaled score of 8. After you obtain scaled scores on all of your subtests, you add them up and (say) get a sum of scaled scores of 90. When you take this to the FSIQ charts, this comes out as a standard score of 95, in the Average range. We then say your IQ is 95.
Posted by: Aden

Re: CogAT to IQ - 08/23/18 12:22 PM

And is there any chance of finding these tables, or are they usually kept confidential by psychologists?
Posted by: aeh

Re: CogAT to IQ - 08/23/18 01:04 PM

The tables are the intellectual property of Pearson, the publisher. There is no reason you would need to see them if you are not an assessment professional. If you have other specific questions relating to scores or scoring, I would be happy to try to answer those that can be answered ethically, but perhaps backchannel. Feel free to pm me.
Posted by: Aden

Re: CogAT to IQ - 08/23/18 01:36 PM

Ok. Sorry for asking about the tables. Thank you so much for your help!
Posted by: aeh

Re: CogAT to IQ - 08/23/18 02:20 PM

You are welcome. Keep using your curiosity to learn and solve problems!