Articles
To read before, and after, the test
What IQ is, why a result comes with a margin, what training does and what it doesn’t. Short articles, with the sources at the end.
Articles
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Limits
How can I find out my IQ?
To find out your IQ you need to take a standardized test, which compares your performance with people of your age. There are two routes: a test given by a psychologist, which ends in a formal report, and an online test, which gives an estimate with a margin of error.
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How to tell if an online IQ test is reliable
An online IQ test is reliable when it says who you are compared with, shows the margin of error and has enough questions to measure. If it gives an exact number after a few questions, or puts almost everyone above 130, be suspicious.
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Fundamentals
What IQ do you need to join Mensa?
Mensa does not use a fixed IQ number: it admits people at the 98th percentile or above, that is, in the top 2% on a test it accepts. On a scale with a standard deviation of 15, like the Wechsler scales, that is about 131.
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History
What was Einstein's IQ?
No one knows. We found no record that Albert Einstein ever took an IQ test, and the numbers that circulate, such as 160, come without any source of measurement. He is also not in Catharine Cox's 1926 study, which estimated the IQ of historical figures.
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Fundamentals
Does a high IQ guarantee success?
It does not. IQ predicts years of education, type of occupation and income on average, but the link with income is weak. In a 2007 meta-analysis, the correlation was 0.56 with education, 0.43 with occupation and 0.20 with income.
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Free or paid IQ test: what changes?
Being free or paid does not tell you whether an IQ test is good: the method does. There are free instruments built by researchers, and paid tests that give a number with no margin of error. Before paying, check what you get and whether the charge repeats.
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IQNorth or myIQ: how the two tests differ
IQNorth and myIQ are different companies. Both tests have 40 questions and take about 20 minutes; the main difference is the yardstick: myIQ says your percentile is calculated among people who took its test, while IQNorth compares you with the population curve for your age group and shows a 95% range.
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Fundamentals
What IQ is, and what it isn't
IQ is a position on a scale, calculated by comparing you with people your age. Knowing where that number came from helps you read what it tells you and what it leaves out.
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Fundamentals
What each score means: 85, 100, 115, 130
Every IQ score marks a spot on a curve with an average of 100 and a standard deviation of 15. Knowing how to read that spot helps you avoid the most common traps in online results.
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Method
Why an honest result comes with a margin of error
No test measures without error. Showing the range where the result most likely falls is how you say how much that number deserves to be trusted.
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Method
Why 40 questions, not 10 or 150
The length of a test decides how much it errs and how much it tires you out. IQNorth's 40 questions are the point where both are acceptable at the same time.
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Method
Item Response Theory without the formulas
The same family of models that scores the ENEM, Brazil's national high school exam, calculates IQNorth's estimate. The idea fits in a few pictures, with no equations at all.
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Online reasoning test or consultation with a psychologist
Both talk about IQ, but they answer different questions. Knowing which is which keeps you from using a number for a decision it can't support.
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History
The Flynn effect: why IQ norms grow old
For much of the 20th century, each generation did better than the last on reasoning tests. In some countries the rise stopped and turned into a decline, and that changes how a norm has to be built.
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Evidence
Does training raise IQ? What the meta-analyses say
Practicing one kind of exercise almost always makes you better at it. The open question is whether that gain carries over to reasoning in general, and the best reviews say it barely does.
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Method
Why retaking the test almost always comes out “stable”
People who retake a reasoning test usually do a little better the second time, even when nothing has changed. That is why an honest retest starts by discounting that gain.
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Fundamentals
Reasoning and age: what changes and what stays
Reasoning about new problems and accumulated knowledge follow different curves over a lifetime. That is why the same performance means different things at 25 and at 65.
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History
How Catharine Cox estimated the IQ of historical figures in 1926
In 1926, a Stanford psychologist tried to estimate the IQ of about 300 historical figures by reading what was known about their childhoods. The study is fascinating, and far shakier than the internet usually lets on.
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Areas
Working memory: what it is and how much it holds
Working memory is the space where you hold information while you do something with it. It is small, it runs out fast, and it is closely tied to reasoning.
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Areas
Reasoning matrices: from Raven to the rules
A grid of figures with one empty space and a hidden rule. The format John Raven created in 1938 is still the classic way to measure abstract reasoning.
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Beyond IQ
The Big Five personality traits
Personality is not ability. The Big Five traits describe typical ways of feeling, thinking and acting, and they grew out of a simple idea: the words we use to describe people.
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