What is an IQ Test? What is an Accurate IQ Test?

While people have different cognitive strengths and weaknesses (e.g. language, music, math, visual), consistent correlations between them show us there is a common component to all of these. This common, underlying factor is called ‘general intelligence’ or ‘g‘.

g is measured with a variety of psychometric assessments that are often referred to as “IQ tests”.

IQ tests are the most reliable (e.g. consistent) and valid (e.g. accurate and meaningful) type of psychometric test that psychologists make use of. They are well-established as a good measure of a general intelligence or g.

IQ tests are widely used in many contexts – educational, professional and for leisure. Universities use IQ tests (e.g. SAT entrance exams) to select students, companies use IQ tests (job aptitude tests) to screen applicants, and high IQ societies such as Mensa use IQ test scores as membership criteria.

The IQ Score Bell Curve – A ‘Normal Distribution’

With standardized IQ tests, IQ tests are designed so that their scores have a ‘bell curve’ distribution in the general population with an average of 100.  This curve has a peak in the middle where most people score and tapering ends where only a few people score. In statistics this is called a normal distribution. Many variables in nature  (such as height and weight) have a distribution of the same shape.

The area under the curve between scores corresponds to the percentage in the population between those scores. The scores on this IQ bell curve are color-coded in ‘standard deviation units’. A standard deviation is a measure of the spread of the distribution. 15 points is one standard deviation for most IQ tests. Nearly 70% of the population score between 85 and 115 – i.e. plus and minus one standard deviation. A very small percentage of the population (about 0.1% or 1 in 1000) have scores less than 55 or greater than 145 – that is, more than 3 standard deviations out!

What is an Average IQ Score?

Standardized IQ tests are designed so that the exact average (mean)  IQ score in the general population is 100.  An ‘average IQ score’ or ‘normal IQ score’ can be defined as a score between 85 and 115 – between plus and minus one standard deviation from the average. (See the table below.)

What is a High IQ Score? What is Mensa Standard?

An IQ of 115 or more can be considered to be a high IQ score or level. Only 15% of the population have an IQ level of 115 or above.  There is no magic bullet but in general it is thought that:

• An IQ of 110 or above enables you to attain a college level education if you choose it.
• If you have an IQ of 115 or above you are capable of the cognitive demands of almost any profession, and can attain the highest levels of education and training.

The entry score for An IQ of 124 is needed to become a member of the International High IQ Society. This is the first entry-point score into high IQ societies. This is another criterion for a high IQ score.

Around 2% of the population has an IQ greater than 130 which is ‘gifted’ intelligence. This is an IQ of 2 standard deviations from the average IQ. This is Mensa standard –  IQ score on a valid, standardized IQ test required to become a member of Mensa.

IQ Level Scale

This table indicates how IQ levels can be classified. The IQ ranges are conventional ones.