Aren't IQ tests invalid?

Question

Because someone with an IQ under ... say ... 40 couldn't take the test, and thus the bell curve is thrown off.

Answer 1

Not all IQ tests are not standardized. A 131 on one test may be a 148 on another test. They also vary from country to country. A 131 in the US is a 98 in Canada.

Most IQ tests fall under certain categories: Otis-Lennon, Stanford Binet, Henmon-Nelsen, etc. For comparison of standardized tests, Mensa, for example allows anyone to be a member that can show that they are in the top 2%. The Mensa Criteria for top 2% are as follows:

Otis Lennon IQ Test - 132
California Cognitive Skills - 131
ACT Test - 29
SAT - 1300
ARMY GCT - 136
Navy GCT - 68

Answer 2

As far as standard IQ tests, it's pretty fair. Almost all online IQ tests are like this. However, if you've ever taken an IQ test for MENSA, you'll find it's quite a bit more extensive, and a little harder. I know my IQ from the Tickle tests, or other online tests, is a little bit higher, but only 3 to 5 points from what my other scores were.

Answer 3

Scores are statistically distributed using what is called the normal bellcurve. They can use large sample groups to predict the IQ of an any individual in a population with great accuracy.

For the record, most tests only test IQ between 70 and 130. The best tests are capable of a range between 40 and 160. As a rule of thumb, scores under 60 or above 140 usually start to deviate too far from the mean to be reliable or informative. Generally scores outside that range can be summarized as 'Too stupid to take the test' and 'Too smart to be measured by the test'.

But no, IQ tests are not 'invalid'. 99.4% of the population scores between 60 and 140, and within this range fairly accurate scores are usually achievable.

Answer 4

IQ tests administered by a psychologist to a child are quite accurate. IQ tests that are paper exercises given to adults are just statistical malarkey, mostly they measured learned knowledge and acquired skills which is not IQ.

A ten year old child that can only perform at the 4 year old reasoning level has an IQ of 40, and yes that is measurable. It is also very rare, so these people are safely ignored in tests given adults who are mostly concerned that they score as a genius or better.

The thought of a bell (or normal gauss) curve was added later by statisticians and was not part of the original analysis used to develop the IQ test method. It is used by testing organizations to calibrate the tests they give to adults and as you point out that sometimes leads to absurd results.

Answer 5

Many IQ tests have been found full of cultural biases. For example, one test was rejected due to this question: If you went to the grocery store and it was closed, which is the most logical solution? A. Go to the next store. B. Go home. C. blah blah D.Blah blah. (C and D don't matter) Both A and B are correct depending on where you live. A person in the city would go to the next store, whereas somebody living in a rural place may have to drive or walk 50 miles to reach the next store. The IQ tests are just a basic idea and not meant to be taken too seriously.

Answer 6

I think you are confusing a learning curve with an IQ test. Apples and Oranges.

Answer 7

Nope, they correct for that sort of thing so most IQ tests would have a curve centered around 100.

Answer 8

well, people with iq's under 40 havent the smarts to breathe, so....

anyway an iq test is based on the average iq, so it is plenty valid

Answer 9

there should be no curve in an IQ test. it is a standardized test to meassure thinking capability. a curve would make the results of the test useless.

Answer 10

You must mean yourself. Who says the scale starts at zero, Einstein?