Mental Age Vs. Modern Method
German psychologist William Stern proposed a method of scoring children's intelligence tests in 1912. He calculated what he called a Intelligenz-Quotient score, or IQ, as the quotient of the 'mental age' (the age group which scored such a result on average) of the test-taker and the 'chronological age' of the test-taker, multiplied by 100. Terman used this system for the first version of the Stanford-Binet Intelligence Scales. This method has several problems such as the fact that it cannot be used to score adults.
Wechsler introduced a different procedure for his test that is now used by almost all IQ tests. When an IQ test is constructed, a standardization sample representative of the general population takes the test. The median result is defined to be equivalent to 100 IQ points. In almost all modern tests, a standard deviation of the results is defined to be equivalent to 15 IQ points. When a subject takes an IQ test, the result is ranked compared to the results of the standardization sample and the subject is given an IQ score equal to those with the same test result in the standardization sample.
The values of 100 and 15 were chosen to get somewhat similar scores as in the older type of test. Likely as a part of the rivalry between the Binet and the Wechsler, the Binet until 2003 chose to have 16 for one SD, causing considerable confusion. Today, almost all tests use 15 for one SD. Modern scores are sometimes referred to as "deviation IQs," while older method age-specific scores are referred to as "ratio IQs."
Read more about this topic: Intelligence Quotient
Famous quotes containing the words mental, age, modern and/or method:
“Libraries are reservoirs of strength, grace and wit, reminders of order, calm and continuity, lakes of mental energy, neither warm nor cold, light nor dark. The pleasure they give is steady, unorgastic, reliable, deep and long-lasting. In any library in the world, I am at home, unselfconscious, still and absorbed.”
—Germaine Greer (b. 1939)
“The United States is just now the oldest country in the world, there always is an oldest country and she is it, it is she who is the mother of the twentieth century civilization. She began to feel herself as it just after the Civil War. And so it is a country the right age to have been born in and the wrong age to live in.”
—Gertrude Stein (1874–1946)
“I am not afraid of the priests in the long-run. Scientific method is the white ant which will slowly but surely destroy their fortifications. And the importance of scientific method in modern practical life—always growing and increasing—is the guarantee for the gradual emancipation of the ignorant upper and lower classes, the former of whom especially are the strength of the priests.”
—Thomas Henry Huxley (1825–95)
“The method of authority will always govern the mass of mankind; and those who wield the various forms of organized force in the state will never be convinced that dangerous reasoning ought not to be suppressed in some way.”
—Charles Sanders Peirce (1839–1914)