intelligence quotient or IQ

IQ is a measure of relative intelligence determined by a standardized test. The first intelligence test was created in 1905 by Alfred Binet and Simon to determine which French school children were too slow to benefit from regular instruction.

Mental Age/Chronological Age X 100 = Intelligence Quotient

The majority of people have an IQ between 85 and 115.

I.Q. (intelligence quotient) in general, is an assessment of your ability to think and reason. IQ score is a standardized way of comparing this ability with the majority of people the same age as you are. A score of 100 means that compared to these people in your general age group that you have basically an average intelligence. Most psychologists would say those scoring in a range of 95 to 105 are of a normal intelligence or have an average IQ. Actual IQ score may vary plus or minus five points since it is very difficult to get an IQ score with complete accuracy. Keep in mind, there are many outside factors that may have a negative impact on your score. For instance, if you are not feeling well at the time of taking the test. Or perhaps you are distracted by something on that particular day.

IQ scores are used as predictors of educational achievement, special needs, job performance, and income. They are also used to study IQ distributions in populations and the correlations between IQ and other variables.

There are a variety of individually administered IQ tests in use in the English-speaking world. The most commonly used individual IQ test series is the Wechsler Adult Intelligence Scale for adults and the Wechsler Intelligence Scale for Children for school-age test-takers. Other commonly used individual IQ tests include the current versions of the Stanford-Binet, Woodcock-Johnson Tests of Cognitive Abilities, the Kaufman Assessment Battery for Children, the Cognitive Assessment System, and the Differential Ability Scales.

Reliability and validity

Psychometricians generally regard IQ tests as having high statistical reliability. A high reliability implies that—although test-takers may have varying scores when taking the same test on differing occasions, and they may have varying scores when taking different IQ tests at the same age—the scores generally agree with one another and across time.

IQ scores can differ to some degree for the same person on different IQ tests, so a person does not always belong to the same IQ score range each time the person is tested.

IQ can change to some degree over the course of childhood.

Environmental and genetic factors play a role in determining IQ. Their relative importance has been the subject of much research and debate.

Musical training in childhood has been found to correlate with higher than average IQ.

The ratio of brain weight to body weight and the size, shape and activity level of different parts of the brain, the total amount of gray matter in the brain, the overall thickness of the cortex and the glucose metabolic rate may affect IQ.