IQ scores and differences between groups

 

IQ scores

Your IQ score indicates how you have performed on an IQ test in comparison with a norm group. For example with a Dutch IQ test, the Dutch or the Dutch work force could be the norm group. If you take an IQ test on an American site, your IQ score most likely will be the result of a comparison with Americans.

The norm group with which your test score is compared, has an average score of 100 and a standard deviation of 15. A standard deviation is a measure of the spread, in this case of the IQ score. If the standard deviation is 15, 68 percent of the norm group scores between 85 (100 minus 15) and 115 (100 plus 15). In other words: 68 percent of the norm group has a score within one standard deviation of the average (100).

In addition, 95 percent of the norm group has an IQ score within two standard deviations of the average. Thus 95 percent of the norm group, for example the Dutch, scores between 70 (100 minus 30) and 130 (100 plus 30). Only 2.5% of the norm group will achieve a score above 130. Purely on the basis of chance and given the fact that the Netherlands has a population of 16 million, it is likely that there are no more than 25 people with an IQ of 170. A person with an IQ of 180 is likely to be the only one in the Netherlands. Only 4 out of 1000 people have an IQ of 140 or higher.

However, with a lot IQ tests on the Internet it is relatively easy to achieve a score higher than 130. These tests often have another purpose, for example gathering marketing information.

IQ score differences between groups

Intelligence and IQ scores have been the subject of an enormous amount of research. Over time a number of conclusions has been reached, some of them interesting, some simply funny and some very controversial. Some of these conclusions are listed below.

Sex

Men tend to score higher than women. This could be in part caused by the fact that IQ tests traditionally measure things at which men are better than women. For example, think about spatial insight and math. If there is more of a balance between things at which both men and women are good, the differences between sexes could disappear.

Age differences in IQ scores

In comparison to the entire population, your IQ score will increase until you reach 'adulthood' and will decrease as you get older. This is simply a consequence of the maturation of the brain and an increasing understanding and vocabulary.

As people get older, it becomes more difficult to focus and the quality of their memory decreases. This leads to a decrease in performance, although the absolute decrease is often minor.

Education

It will not come as a surprise that people with a higher educational level score higher in IQ tests than people with less education.

Race

This is a very charged topic. If you wrongfully assume that intelligence is a matter of genetics only, differences between races could be used to justify racism. After all, Asians on average score higher than whites in a traditional IQ test. And whites in turn score higher than blacks.

It is very unlikely that intelligence as it is measured is hereditary only. There are numerous other factors which could explain the differences found. Factors like culturally determined attitude towards work, socioeconomic status, health and educational differences are divided unequally between races. In fact it would be illogical if no differences would be found between races.

Nationality

According to 'popular belief' some nations are not as smart as others. There are many differences in IQ scores between countries. The primary cause is the educational level. The 'higher educated' a country is, the 'smarter' the country is.

Social success

Although a lower IQ score does not in itself prevent social success, successful people do more often have a higher IQ.

Read more on the hereditary aspect of intelligence or take an IQ test.