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jastu
02-27-2004, 05:56 PM
I have only ever taken one IQ test, it was a standard Mensa test with a top score of 150. At the time I thought I did very well but have since met many average Americans who claim to have IQs in the area of 170, 180.

Obviously there are different IQ tests around but do they all use the same scale? I am a little confused.

alice_in_wonderland
02-27-2004, 06:10 PM
No - there are different types of IQ tests.

Here are a few facts, FWIW:

The average IQ (in it's traditionally accepted defintion) is 100 with a SD of 15. Only 2% of the population has an IQ more than 2 standard deviations over the mean - that is to say, over 130.

If you're meeting hoards of people who claim to have IQ's in the 170's and 180's, you're either hanging out with exceptionally smart people or a bunch of liers (or exagerators).

The various IQ tests have differing numbers of questions. When a person writes the test there score is standardized to where the mean score of all test takers is 100 and that results in their IQ. In order to determine how well you did on the MENSA test you would need to know the mean score as well as the SD on that particular test. You could then determine where you stand in relation to your peers, as well as the population as a whole.

Finally, IQ's falling between 1 SD above or below the mean will not mean a huge amount to a persons abilities or successes in life - a person with an average IQ can be wildly successful or horribly inept - there are many other factors that determine success. It's only when IQ's rise or fall in the extreme ends of the scale that you see radical performance deficits or advantages.

Sattua
02-27-2004, 09:33 PM
Reference The Bell Curve by Richard Hernnstein and Charles Murray.

These people probably took their IQ tests online, which isn't valid. You've gotta have the real sit-down, supervised test to know.

conczepts
02-27-2004, 09:36 PM
Those online IQ tests seem to always score higher than average...the average online IQ score seems to be in the 140 range from what I've seen on other forums where a large sample of people took the test and posted their results.

I got 180 on the same test, and I really doubt that I would get that high on a 'legitimate' supervised IQ test. I think the online tests score you higher intentionally because after they give you your score, they offer to sell you an in-depth "analysis" of your results. Obviously a person who got a higher score is more likely to buy this than the guy who gets 100 or less.

Achernar
02-28-2004, 01:45 AM
If you're meeting hoards of people who claim to have IQ's in the 170's and 180's, you're either hanging out with exceptionally smart people or a bunch of liers (or exagerators).
Statistically speaking, about one person in 160,000 has an IQ above 170, and about one person in 5.2 million has an IQ above 180. I don't know how accurate the formula (or the conpect of IQ!) really is at these extreme ranges, but that's what it gives.

drhess
02-28-2004, 02:06 AM
Reference The Bell Curve by Richard Hernnstein and Charles Murray.

These people probably took their IQ tests online, which isn't valid. You've gotta have the real sit-down, supervised test to know.

That book is a horrible one to recommend on the topic. Better would be just any standard college textbook on developmental psych or testing. (For more technical stuff there is a book out there called "The Rising Curve" that is very interesting.)

jastu
02-28-2004, 10:57 PM
Thank you all for your replies and helpful information.

I have been very surprised over the years to have met so many people who claimed these high IQ's, all from the US thus the confusion. Perhaps they did take their tests online, perhaps they were exaggerating. Even though the subject doesn't come up very often, in future I will ask where & when they took their test.

Lamia
02-28-2004, 11:32 PM
Since IQ score is determined by how well one does compared to the rest of the general population, not simply by the number of right answers, the tests aren't accurate beyond a certain point. (Of course, some would argue they aren't accurate at all, but that's another issue.) If, as Achernar explains, one person in 5.2 million has an IQ of 180, the only way to be sure your test accurately measured that high would be to give it to 5.2 million people. This isn't practical, so real IQ tests settle for accuracy over a smaller range of scores. IIRC, the Stanford-Binet tops out at 160 and the WISC at 140. It's possible to do better than that, it's just not possible to assign a solid number score to such high performance.

Some of the people you know claiming to have IQs of 170 or 180 are probably outright liars. Others took online "IQ tests", which have about as much value as a "What Pokemon character are you?" quiz. However, there may be some who legitimately earned those scores on old IQ tests. Back in the day, IQ tests administered to children used an age-based formula. (This was before my time, but these tests were once commonly given to schoolchildren and most Americans of a certain age probably had them.) A six-year-old who performed as well as the average six-year-old would get a score of 100, but a six-year-old who performed as well as the average twelve-year-old would get a score of 200. So a score of 170 for a bright kid isn't too far-fetched, one just has to remember that it does not correspond to a 170 on a different test.

dauerbach
02-29-2004, 01:14 AM
One thing that I have never been able to figure out is how anyone can have a test report an IQ of, say, 175. That is five standard deviations above the mean, and there is no way that a test can accurately reflect that degree of deviation.

Also, let's say that there are 100 questions and each has four answers. Therefore the lowest possible score it 25. Therefore, only 75 questions give information. Let's guess that an IQ of 140 has 95 correct. That leaves five questions to differentiate between all IQ's over 140, clearly an absurd idea. You get 95 correct you are very smart, get three more right and you are a genius. I don't think so.

Lamia
02-29-2004, 02:15 AM
One thing that I have never been able to figure out is how anyone can have a test report an IQ of, say, 175. That is five standard deviations above the mean, and there is no way that a test can accurately reflect that degree of deviation.


No one can have an IQ test score that high. Anyone claiming to have such a score either took a now-outdated test scored with a different system, a completely bogus test (like any online "IQ test"), or is just a liar.


Also, let's say that there are 100 questions and each has four answers. Therefore the lowest possible score it 25. Therefore, only 75 questions give information. Let's guess that an IQ of 140 has 95 correct. That leaves five questions to differentiate between all IQ's over 140, clearly an absurd idea. You get 95 correct you are very smart, get three more right and you are a genius. I don't think so.

FWIW, none of the major IQ tests currently accepted by the psychological community are multiple choice.

iamthewalrus(:3=
02-29-2004, 02:41 AM
Also, let's say that there are 100 questions and each has four answers. Therefore the lowest possible score it 25. Therefore, only 75 questions give information.

I'm not sure how you came to that conclusion. It's certainly possible to score worse than average on a multiple-choice test. In fact, good multiple-choice tests have questions that nearly everyone will get wrong because they have some incorrect, but seemingly correct, answers included in the set of responses.

If you look at, say, the GRE, there are always a few questions that only single digits of respondants answered correctly. Make up a test of those, and you could certainly score worse than random.

dauerbach
02-29-2004, 06:25 AM
Walrus,

I have to disagree with you there. You will agree that in a multiple choice test with 4 possible answers to each of 100 questions that a planarian would, on average, get a 25. Getting less than that cannot be meaningful. And I would say those questions that only a few percentage get right are trick questions, where you must analyze the syntax of the statement, or must think exactly like the test writer did. While you may agree that the stated answer is the best one, for a myriad of reasons most were "fooled." I maintain that is a bad rather than excellent question.

dauerbach
02-29-2004, 06:31 AM
Also, saying there are questions that most taking the Graduate Record Examinations will get wrong is hardly a chilling statement. When talking about the ability to differentiate high IQ's (whatever those are), the subset that is those taking the GRE's is hardly elite.

ianzin
02-29-2004, 10:39 AM
To answer the OP, there are many different IQ tests around. They are not consistent, and not intended to be, and indeed it is very doubtful whether they actually measure anything useful at all. If you sit a given IQ test and get a score of 125, pretty much all you know is that on that test, on that day, you scored 125. You haven't learned anything at all about how intelligent you are. In fact, it's very difficult to come up with any meaningful way of assessing 'intelligence'. Gould's book 'The mismeasure of man' is a good one to read if you're interested in the history of IQ tests and how they have been abused to suit given political ends.

Mathochist
02-29-2004, 11:46 AM
Also, saying there are questions that most taking the Graduate Record Examinations will get wrong is hardly a chilling statement. When talking about the ability to differentiate high IQ's (whatever those are), the subset that is those taking the GRE's is hardly elite.

Sounds like someone has it out for academia.

Be that as it may, the GRE is indeed rather toothless these days. When I took it, it was basically the same as the SAT -- sections dependant on computational mathematics and vocabulary -- with the addition of a "logic" section which I enjoyed immensely. The GRE just went into slightly more difficult territory (the math topped out at a smattering of calculus, rather than geometry).

As I hear, they've removed the logic section, so anyone at all can ace the GRE if they have a solid handle on the calculus and have read a good selection of everything written in the last couple centuries (to boost vcabulary).

Really Not All That Bright
02-29-2004, 11:59 AM
You need calculus to pass the GRE?


Well I'm not going to f-ing grad school anymore...

FWIW, when I was seven I took the Mensa test in the UK, and based on the age bonuses I ended up with a 170. I haven't taken a test recently (never actually joined) but while I'm smart, I'm pretty sure I'm not that exceptional.

Mathochist
02-29-2004, 12:03 PM
You need calculus to pass the GRE?

No, just to score 2400.

Ilsa_Lund
02-29-2004, 12:06 PM
I have taken several tests, from MENSA to online tests and have scored between 150 and 180. (I think I got a 153 on the MENSA) I started college at twelve. YMMV.

Ilsa_Lund
02-29-2004, 12:08 PM
No, just to score 2400.

What kind of calculus?

Mathochist
02-29-2004, 12:12 PM
What kind of calculus?

When I took it, just some basic single-variable differential and integral calculus. Maybe something on sequences or series IIRC.

Tigers2B1
02-29-2004, 02:15 PM
To answer the OP, there are many different IQ tests around. They are not consistent, and not intended to be, and indeed it is very doubtful whether they actually measure anything useful at all. If you sit a given IQ test and get a score of 125, pretty much all you know is that on that test, on that day, you scored 125. You haven't learned anything at all about how intelligent you are. In fact, it's very difficult to come up with any meaningful way of assessing 'intelligence'. Gould's book 'The mismeasure of man' is a good one to read if you're interested in the history of IQ tests and how they have been abused to suit given political ends.

Well, if Gouldís book carries that much weight in academia, you had better get his ideas over to the Supreme Court Justices and quick! Or better, into the hands of a few of those ivy league, high-powered defense attorneys. Why? IQ scores are presently being used by the courts when determining who is and who isnít eligible for the death penalty. Thatís right, issues of who lives and dies may rest solely of the results of an IQ test.

Sattua
02-29-2004, 02:33 PM
I took the GRE 18 months ago and there was *no* calculus, so relax. Also, while the logic section is gone, it's been replaced by a reasoning section. They give you problems, you write essays explaining your solutions to them. I'm not in a position to say if it's harder or easier.

Don't get me started on The Mismeasure of Man. If you score 125 on a real, proctored IQ test, you're above average period.