Why is the average IQ 100?
IQ tests set 100 as the mean when they create their scoring norms. Test makers compare results with a reference group, then set the scale so that the group’s average is 100. The number marks the center of that scale.
This makes 100 a feature of how an IQ test is scored, not an absolute measurement of intelligence. A score shows a person’s position relative to that test’s norms. The test and the group used to create its norms give the score its context.
How many people score near 100?
On a scale with a mean of 100 and a standard deviation of 15, about 68.3% of scores fall between 85 and 115, and about 95.4% fall between 70 and 130. These shares describe how normed scores are distributed around the mean.
A range describes the spread of scores, not the result any one person will get. Scores farther from 100 are less common in this reference distribution, but that alone does not describe a person’s skills or circumstances. See IQ standard deviation for how the spread is measured.
Why does the average stay 100 as scores rise?
The average stays at 100 because test makers update their norms and reset the scale. IQ test scores have drifted upward across decades, a pattern called the Flynn effect. Estimates differ between analyses, so the trend does not have one fixed rate.
When a test is renormed, its results are compared with a current reference group and the scale is adjusted so that group’s mean is 100. This ties scores to the newer norms. The Flynn effect page explains the upward trend and its relevance to comparing scores over time.
Does average IQ vary by age?
On an age-normed test, the average is 100 for each age group because test-takers are compared with people in their own age group. An IQ score therefore compares a person with age peers, rather than directly comparing raw answers across ages.
Different age groups may take different questions or tasks, so equal IQ scores do not mean the test-takers gave the same answers. They indicate a similar relative position within their respective age norms. The average IQ by age page explains this comparison.
Why is there no average IQ by country table?
IQClock does not publish an average IQ table by country because published country figures are contested and combine different tests and samples. Putting them in one ranking could imply that the underlying results are directly comparable.
The test used and the people who took it can differ between reported figures. Those differences make a simple country-to-country comparison difficult to interpret. IQClock’s free timed reasoning test offers reasoning questions and does not print an IQ score.