Average IQ Score: What Is Normal?

The average IQ score is always 100, as the distribution of IQ scores is meant to follow a normal distribution around an IQ of 100. However, a normal person’s IQ score is 85 to 115, which is 1 standard deviation away from the average. So if you fall within the IQ range of 85 to 115, you are 1 standard deviation from average and in the “normal” range.

IQ is the acronym of Intelligence Quotient or, in other words, is how we commonly measure intelligence. But what is the average IQ and what is normal as an Intelligence Quotient? In this article, we will answer those questions in detail.

Many people are acquainted with IQ numbers, but very few know what they really are. Understanding IQ scores and knowing how to interpret them is fundamental.

What Is IQ?

Before you are ready to read about the average IQ and what is normal, you need to learn about what IQ is.

The Intelligence Quotient (IQ) is a method whereby we are able to measure a person’s ability to reason and solve different problems.

Measuring intelligence continues to be a controversial topic. There are many heated debates about it in the education and psychology arenas. But, despite all controversies, intelligence tests are still widely used and many people (professionals or otherwise) find them credible.

It is important to note that IQ scores are only of value when predicting academic success but very little else. For example, a person with a lower IQ than somebody else could be more successful in business or in other, non-academic, endeavors. There are many examples of this.

The image of social-IQ combined score distribution was created at Prof. Ben-Jacob’s lab, at Tel-Aviv University, Israel Image source: Wikipedia/Paenigenome licensed under CC-BY-SA 3.0

IQ can be measured using different tests so when comparing people’s IQ scores it is important that we only compare those who have taken the same tests.

If we don’t plant the right things, we will reap the wrong things. It goes without saying. And you don’t have to be, you know, a brilliant biochemist and you don’t have to have an IQ of 150. Just common sense tells you to be kind, ninny, fool. Be kind. – Maya Angelou

Having said all of that, the average score across most tests is 100. But as many as 68 percent of all the scores lie somewhere between 85 and 115.

What are Average IQ Scores?

There are different scoring systems to measure IQ. But most of them use 100 as their average score. Tests then have a deviation of 15 so that the scores follow a distribution curve that is normal.

Here is what else you need to know about average IQ scores.

Because 98 percent of all scores are within the mean standard deviation (between 85 and 115), about 70 percent of people are within only 15 points (plus or minus) of the average score.

Now, 95 percent of all scores fall within 70 and 130, which are the two standard deviations. A very low IQ and that below 70 and a very high IQ is above 130. Only 5 percent of the population combines has either a very low or a very high IQ.

People with a growth mindset believe that they can improve with effort. They outperform those with a fixed mindset, even when they have a lower IQ, because they embrace challenges, treating them as opportunities to learn something new. – Travis Bradberry

Usually, only people with a serious learning or developmental disability will score below 70. And most people who go above 130 can be considered gifted.

How Do They Calculate IQ Scores?

The way that IQ tests are conducted has evolved over the years. But, typically scores come in one of two different methods. The first and oldest method consists of taking what was thought about as the person’s mental age and then dividing it by their chronological age and, finally, multiplying it by 100. The second method has some variations but, mostly, it consists of comparing individual scores with others in the very same age group.

The second method has become standardized and it is what allows us to interpret and compare IQ scores. This is how we can know what they mean. But how does this really work? First, a representative sample of the population takes the same test. The results from those tests are then used to establish the norms, which are the standards. Then the results of each individual can be compared to those norms or standards.

Using 100 as the median score, the individual test scores can be placed within the normal distribution.

Some tests publishers use a scale that places average scores between 90 and 109. In that scale, a score between 110 and 119 would be considered high average, and a score that falls anywhere between 80 and 89 would be classified as a low average.

As we saw most people would score in the region of 100. This is the average score that most people would overwhelmingly get.

But remember that they are different kinds of intelligence. IQ tests only measure what is known as “crystallized and fluid intelligence”.

What is “crystallized and fluid intelligence”? The term “crystallized intelligence” refers to all the skills and knowledge that a person has acquired throughout his or her life (no matter his or her age). The term “fluid intelligence” on the other hand refers to a person’s ability to make sense of things, reason, and solve problems.

Crystallized intelligence tends to grow with age as people accumulate learning experiences while fluid intelligence tends to decline with age and is not related to learning.

What Are the Most Common IQ Tests?

Only licensed psychologists are allowed to administer IQ tests.

There are many different IQ tests, but the most commonly used ones are the following:

  • The Wechsler Intelligence Scale for Children.
  • The Wechsler Intelligence Scale for Adults.
  • The Kaufman Assessment Battery for Children.
  • The Stanford-Binet Intelligence Scales.
  • The Cognitive Assessment System.
  • The Woodcock-Johnson Tests of Cognitive Abilities.
  • The Differential Ability Scales.

Each one of these tests is different enough from the rest, so we should only compare the results of individuals who have taken the same test.

About Juan Ramos

Juan has been writing about science for over a decade and regularly keeps up with technological and scientific advancements. Juan is known for taking complex research and technology and presenting it in an easily digestible form for education. Juan holds a Master's degree from The Open University in the UK.

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