Intelligence quotient (IQ)

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"IQ" redirects here. For other uses, see IQ (disambiguation).
Intelligence quotient
Diagnostics

An example of one kind of IQ test item, modeled after items in the Raven's Progressive Matrices test.
ICD-9-CM 94.01
Human intelligence
Abilities and Traits

Abstract thought
Communication · Creativity
Emotional Intelligence
Knowledge · Learning · Memory
Problem solving · Reaction time
Reasoning · Understanding
Visual Processing
Models and Theories

Cattell-Horn-Carroll theory
Fluid and crystallized intelligence
General intelligence factor
Intelligence quotient
Theory of multiple intelligences
Triarchic theory of intelligence
Fields of study

Cognitive epidemiology
Environment and intelligence
Evolution of human intelligence
Heritability of IQ
Impact of health on intelligence
Neuroscience and intelligence
Psychometrics
Race and intelligence
v · d · e

An intelligence quotient, or IQ, is a score derived from one of several different standardized tests designed to assess intelligence. When modern IQ tests are constructed, the mean (average) score within an age group is set to 100 and the standard deviation to 15.[1] Today almost all IQ tests adhere to the assignment of 15 IQ points to each standard deviation, but this has not been the case historically. Approximately 95% of the population have scores within two standard deviations of the mean. If one SD is 15 points, then 95% of the population would be expected to have an IQ within a range of 70 to 130.

IQ scores have been shown to be associated with such factors as morbidity and mortality, parental social status,[2] and, to a substantial degree, parental IQ. While the heritability of IQ has been investigated for nearly a century, controversy remains regarding the significance of heritability estimates,[3][4] and the mechanisms of inheritance are still a matter of some debate.[5]

IQ scores are used in many contexts: as predictors of educational achievement or special needs, by social scientists who study the distribution of IQ scores in populations and the relationships between IQ score and other variables, and as predictors of job performance and income. The average IQ scores for many populations have been rising at an average rate of three points per decade since the early 20th century, a phenomenon called the Flynn effect. It is disputed whether these changes in scores reflect real changes in intellectual abilities.

Whether or not IQ tests are an accurate measure of intelligence is open to debate. It is difficult to define exactly what constitutes intelligence; it may be the case that IQ scores represent a very specific type of intelligence.