# What is the most common IQ?

I do not care what the average iq is. I want to know what the most common IQ is. I mean...For example:

120
120
120
120
120
120
40
40
Average of all this is 100. But 100 is not the mean IQ. I don't know if the bell curve is just assuming that the most common IQ is between 90-110 simply because that is the average. I hardly know any one in the 90-110 range, and yet I know PLENTY of people in the 120-130 range. I know thats not scientific evidence, but I seriously doubt 50% of everyone is in the 90-110 range. I known two people in that range and lets just say they are not the sharpest knife in the drawer. They can memorize really well though. Just not figureing out things.

Evo
Mentor
You know that internet tests for IQ are not valid. IQ tests must be given by a psychologist trained in administering them and cost thousands of dollars (unless your school pays for it as a needed assessment or insurance covers it for mental health reasons). You may not know anyone that has been given a valid test (these tests take an entire day), sometimes more than a day, depending on what is being administered.

To add to Evo's reply (although everything she said is completely true), IQ is well known to be normally distributed in the population, which means that the average is the same as the most common value (the mode). If we want to be really pedantic, the probability of someone having an IQ of exactly 100 is zero, but an interval centred at 100 will contain a greater proportion of the population than the same interval centred anywhere else, which may be closer to what you mean.

Evo
Mentor
And number nine is correct.

The best answer I can find for your question PWM. This is for WAIS.

In a normal distribution, the IQ range of one standard deviation above and below the mean (i.e, between 85 and 115) is where approximately 68% of all adults would fall.
http://www.sevencounties.org/poc/view_doc.php?type=doc&id=8219 [Broken]..

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FlexGunship
Gold Member
I hardly know any one in the 90-110 range, and yet I know PLENTY of people in the 120-130 range.
Two problems:
1. the likelihood that you actually know anyone's IQ is pretty low. The tests are fairly rare, and
2. you will have a severe observation bias based on your demographic.

collinsmark
Homework Helper
Gold Member
I think some of the confusion might be alleviated with the understanding of how a good IQ test (if there is such a thing) is developed. As Evo and others have pointed out, those Internet IQ tests are meaningless for reasons I hope will become clear momentarily.

In general, an IQ test can contain a list of any questions: any type of questions. But not all types of questions are created equal. So when designing a good IQ test the creator should make the attempt to use the following guidelines:
• Questions should be unbiased as possible, not giving the advantage to anybody of a particular background, race, ethnicity, gender, etc.
• Questions should test problem solving skills, not knowledge, since knowledge is inherently biased.

Although not absolutely necessary to be considered an IQ test, the following guidelines are also usually followed under the premise (which is debatable) that a person with higher intelligence can do simple problems faster than someone with lower intelligence:
• Questions must be simple.
• The test must be administered using a strict time limit (this reason alone invalidates the usefulness of those online IQ tests).
• The test must contain more questions than anybody could possibly answer within the time limit. The test must have so many questions that it is impossible to "ace" the test (anything short of that means something is wrong with the IQ test).
• The test must be designed such that there is no advantage to guessing. Usually this is accomplished by making the test multiple choice. Testees are penalized an appropriate amount for each wrong answer and awarded for each correct answer. For example, if each question contains four choices, 3 points are awarded to the pre-score for each correct answer and 1 point is subtracted for each incorrect answer. That way if the testee randomly guesses on every single question, the resulting pre-score should be near zero.

The next step involves the control group. The control group should be comprised of as many people as possible (the more the better) and should be a statistical representation of the population at large. That's where things get tricky. How do you assemble a large group of people that maintains a statistical representation of the general population? I don't know, but that's the goal anyway. Then each person in the control group is administered the test in a controlled environment (with the specified, strict, time limit). The pre-scores of all the testees are then tallied and recorded.

The final step involves creating a mapping function. The mean pre-score in the control group data maps to an IQ score of 100. Simple as that. The standard deviation of the pre-scores data of the control group is calculated. This pre-score standard deviation maps to an IQ standard deviation of 15. Using this mean and standard deviation mapping, a Gaussian normal curve is created to map pre-scores to IQ scores. The end result is a look-up-table. The index of the look up table is the pre-score, and the corresponding table element value is the IQ score. That completes the process of creating an IQ test.

When the test is then administered to someone, it must be administered in same controlled environment setting as the control group (and with the same time limit). This is another reason that invalidates the usefulness of those online IQ tests. When completed, the testee's pre-score is tallied and then mapped to to the IQ score using the look-up-table.

By the way, on a separate but related note, it is a fallacy to say "my IQ is...," or "so and so has an IQ of..." People do not have and IQ. An IQ is not something that actually exists that people can have. It is better to say, "I received this score on an IQ test," or "so and so scored this when taking an IQ test."

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WannabeNewton
Wow...well hopefully you were just kidding around with this comment

Danger
Gold Member
Wow...well hopefully you were just kidding around with this comment
Don't worry; his sense of humour grows on you after a couple of years. :tongue:

In my house, the average IQ is mine. I say that only because Lucy spends a very slightly larger percentage of the day asleep than I do. That could switch over without notice.

My IQ score is 130, better than my usual of 115.:surprised

Danger
Gold Member
My IQ score is 130, better than my usual of 115.:surprised
Did you get a special for presenting a coupon?

wukunlin
Gold Member
apparently my IQ is 50

Sounds kind of low but my brother's IQ is about 150 but that was taken a while back not sure if it also depends on if they use the same for lack of better words grading system

FlexGunship
Gold Member
Wow...well hopefully you were just kidding around with this comment
Don't worry; his sense of humour grows on you after a couple of years. :tongue:.
Okay, I guess... if you're talking about really big photons... I mean big... like the size and speed of a dead cat...