Facts about IQ

All the information and facts about how serious IQ tests work.

The intelligence quotient (IQ) is a measure of a person's intellectual ability. In short, IQ describes the intelligence of a human being.

IQ was originally defined as the ratio of actual age to intelligence age. For example, there are 15 year olds who have an intelligence age of 20 and conversely 20 year olds who have an intelligence age of 15. To improve comparability IQ has been defined as the deviation of cognitive performance from the average of people.

The IQ describes the deviation from the mean or average. In addition IQ is always determined by age group. This is necessary because a 20-year-old who is among the 2% most intelligent people in his age group is not the same as a 30 year old who is also one of the 2% most intelligent people in his age group. Both may have an IQ of 130 (according to their age group), but the 30-year-old is likely to do better on an IQ test.

IQ, as a result of an IQ test, therefore is a measure of intelligence compared to a meaningful number of people of the same age.

IQ can be calculated using the normal distribution. In most iq ests, the mean is set at 100 because the average IQ is 100. As the Gaussian bell curve shows, the majority of people tested have an IQ in the range around 100. The standard deviation is usually set at 15. The standard deviation is the average distance from the mean value.

IQ distribution

Interpretation of the graf

  • 68% of those tested have an IQ between 85 and 115
  • 2% of those tested have an IQ over 130
  • 2% of those tested have an IQ under 70
  • 96% of those tested have an IQ between 70 and 130

Attention to IQ tests!

There are lots of IQ tests out there, online, in books, for free and for a lot of money. But not all IQ tests are the same and not all give an accurate result. Different results usually come from different scales and calculation methods. European tests usually use the method described above, but other tests often have different scales that give different results. American tests often have different scales, which can lead to IQ scores of over 200 points.

It would therefore be advisable not to see result of an IQ test as an absolute result or an absolute number, but to take a more differentiated approach.

For example, IQ can be classified as follows:

  • 80 - 90 = below average
  • 91 - 110 = average
  • 111 - 121 = über Durchschnitt
  • 122 - 130 = above average
  • 131 - 141 = mastermind
  • 141 + = genius

It should also be noted that most (all) tests taken alone in a short period of time cannot provide a result that can be equated with a psychological assessment. In order to obtain an accurate result, it is best to consult an expert who deals exclusively with IQ tests.

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