Facts about IQ


IQ is an acronym for 'Intelligence Quotient', is a total score derived from several standardized tests designed to assess human intelligence, or is a measurement of your intelligence and is expressed in a number. OR  IQ is a number representing a person's reasoning ability (measured using problem-solving tests) as compared to the statistical norm or average for their age, taken as 100.

*Intelligence means the capacity of mind, especially to understand principles, truths, facts or meanings, acquire knowledge, and apply it to practice; the ability to comprehend and learn.

*Quotient means a degree or amount of a specified quality or characteristic, or a result obtained by dividing one quantity by another. 'Quotient' comes from Latin word "Quotiens" meaning 'How many times', "quot"= 'how many' and "iens"= 'times'.

The abbreviation "IQ" was established by the psychologist William Stern for the German term 'Intelligenz quotient', his term for a scoring method for intelligence tests at University of Breslau he advocated in a 1912 book.

IQ is a score obtained by dividing a person's mental age score, obtained by administering an intelligence test, by the person's chronological age, both expressed in terms of years and months. The resulting fraction is multiplied by 100 to obtain the IQ score.

When current IQ tests were developed, the median raw score of the norming sample is defined as IQ 100 and scores each standard deviation (SD) up or down are defined as 15 IQ points greater or less, although this was not always so historically. By this definition, approximately two-thirds of the population scores are between IQ 85 and IQ 115. About 2.5 percent of the population scores above 130, and 2.5 percent below 70.

Intelligence tests scores are estimates of intelligence. IQ scores have been shown to be associated with factors such as morbidity, mortality, parental social status, and biological parental IQ. While the heritability of IQ has been investigated for nearly a century, there is still debate about the significance of heritability estimates and the mechanisms of inheritance.

Intelligence quotient scores are used for educational placement, assessment of intellectual disability, and evaluating job applicants. Even when students improve their scores on standardized tests, they do not always improve their cognitive abilities, such as memory, attention and speed.

In research contexts they have been studied as predictors of job performance, and income. They are also used to study distributions of psychometric intelligence in populations and the correlations between it and other variables. Raw scores on IQ tests for many populations have been rising at an average rate that scales to three IQ points per decade since the early 20th century, a phenomenon called the Flynn effect. Investigation of different patterns of increases in subtest scores can also inform current research on human intelligence.

Before IQ tests, there were attempts to classify people into intelligence categories by observing their behavior in daily life. Those forms of behavioral observation are still important for validating classifications based primarily on IQ test scores. Both intelligence classification by observation of behavior outside the testing room and classification by IQ testing depend on the definition of "intelligence" used in a particular case and on the reliability and error of estimation in the classification procedure.

The English statistician Francis Galton made the first attempt at creating a standardized test for rating a person's intelligence. A pioneer of psychometrics and the application of statistical methods to the study of human diversity and the study of inheritance of human traits, he believed that intelligence was largely a product of heredity.

Galton hypothesized that there should exist a correlation between intelligence and other observable traits such as reflexes, muscle grip, and head size. He set up the first mental testing centre in the world in 1882 and he published "Inquiries into Human Faculty and Its Development" in 1883, in which he set out his theories. After gathering data on a variety of physical variables, he was unable to show any such correlation, and he eventually abandoned this research.

In the early 1900's French psychologist Alfred Binet created the first intelligence test, however, modern IQ testing in the United States stems from the work of Henry Herbert Goddard. Goddard was a psychologist who earned his doctorate in psychology from Clark University in 1899. He translated the Binet test from French to English. This test was used to test basic intellectual functions in U.S. school children and to support mental health diagnoses.

Alfred Binet was one of the key developers of what later became known as the Stanford Binet test. Alfred Binet, together with Victor Henri and Théodore Simon had more success in 1905, when they published the Binet-Simon test, which focused on verbal abilities, it was intended to identify mental retardation in school children.

The score on the Binet Simon scale would reveal the child's mental age. For example, a six-year-old child who passed all the tasks usually passed by six-year-olds but nothing beyond would have a mental age that matched his chronological age, 6.0. Binet thought that intelligence was multifaceted, but came under the control of practical judgment.

Today, there are numerous IQ tests that are used for different purposes, but most are used to help diagnose learning disabilities. Since Goddards controversial Binet tests, psychologists have worked to develop numerous other tests. Most are intended for elementary school-aged children, but some may be used for adults. The following are some of the IQ test commonly used today;

1. Stanford-Binet Intelligence Scale
2. Universal Nonverbal Intelligence
3. Differential Ability Scales
4. Peabody Individual Achievement Test
5. Wechsler Individual Achievement Test
6. Wechsler Adult Intelligence Scale
7. Woodcock Johnson III Tests of Cognitive Disabilities

NB:
It is important to know that 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.

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Posted by: Lusubilo A. Mwaijengo

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