Is Online IQ Test Reliable? I Verified it

English ver

Have you ever tried an online IQ test?

There are many tests to estimate your IQ on the Internet, and International IQ Test is one of them.

In this test, you’ll be asked 40 interesting questions. Most of them is about finding patterns like the image below.

It took about an hour for me to finish the test.

After that tough work, unexpectedly, you will find that you have to pay 5 euro with PayPal or credit card to get my score. When I was asked to pay 5 euro, I wondered if I should pay or not. I guess most of the test-takers had the same questions as mine.

So, I search the Internet. But unfortunately, what I can find is only that it doesn’t seem to be a fraud. Though I don’t have to worry about being hacked my PayPal account, it still remained questionable if I can trust the result.

That’s why I decided to verify if the test is reliable or not.


Now, I’ll show you how I examined.

Get a number of Scores

First, I got the scores of about 3000 test-takers of the test. When analyzing something, it’s inevitable to investigate samples.

That would be too tough to do my own, so I did this task using a powerful technique: web scraping. I believe this decision was right, but it’s not easy for me because I’m not familiar with programming at all. It’s was a far more challenging task than I expected, but anyway I got it done.

Make a graph

Second, I made a graph based on the data that I extracted from the site. Please look at the graph below.

The horizontal axis represents the IQ score of the test-takers, and the vertical axis represents the number of test-takers who got each score.
For example, 104 people got 100 on the test.

Do you find any deficits at a glance? Me, too. I wondered if I can conclude that the test is dubious, but eventually, I decided to continue this examination.

The Average IQ score and the standard deviation

Third, I calculated the average IQ score and the standard deviation.
I got 110.2 as the average IQ score and 16.3 as the standard deviation. You know, it suggests the test uses not 24 but 15 as the standard deviation of IQ score.

This average IQ score must be remarkably accurate. This accuracy is assured by the wisdom of statistics: central limit theorem. I’ll avoid going into the detail of it, but here’s a thing I want you to know. The true value of the average score should be between 119 to 111 with over 99% accuracy. So, it’s almost impossible to insist that the average IQ score in the test is 100.

Compare to the normal distribution

Then, I checked if the distribution of the IQ scores of the test follows the normal distribution. It is one of the most crucial points in judging the reliability of the data whether it follows the normal distribution or not. This time, I took two types of approaches. One is to check visually by making graphs, and the other is to check mathematically by doing statistical tests. For people who don’t familiar with the “statistical test”, I’ll explain the essence of it. A statistical test is used to examine how reliable an assertion is.

Please look at the graph below.

It shows the distribution of the scores of tast-takers (blue) and the normal distribution with mean 100 and standard deviation 15 (light orange). The latter is said to be an ideal distribution of IQ.
Looking at the graph above, we can find a great difference between them. It’s hard to say the distribution follows the ideal one.

Then, let’s move on to statistical tests. I used two types of statistical tests: Anderson-Darling test and Shapiro-Wilk test. Please don’t worry. You don’t need to understand them. What I want to show is only the fact these tests tell us; it is extremely unlikely that the distribution of the scores follows the normal distribution. If it does, it is as rare as the situation in which planes you get on crushes 4 or more consecutive times.


In conclusion, it’s hard to estimate your IQ score accurately with the test. But I guess it’s not easy to improve a system to calculate IQ score. I’m rooting for the development team of the test.

Editor’s Note

My score of the test was 136. I was surprised at it because it a far higher than I expected.

When assuming the result is right, the score means that I’m in a top 0.82%. It was unbelievable. Now I’m relieved to know that I’m not one of “special people.”

I’m on the way to learn English, and I know that my English needs to be improved. When you find any mistakes, strange expressions, and things like that, please let me know in the comment below.

The image at the top of this post is fromBusiness vector created by studiogstock –