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:
“It is human agitation, with all the vulgarity of needs small and great, with its flagrant disgust for the police who repress it, it is the agitation of all men ... that alone determines revolutionary mental forms, in opposition to bourgeois mental forms.”
—Georges Bataille (1897–1962)
“Do not go gentle into that good night,
Old age should burn and rave at close of day;
Rage, rage against the dying of the light.”
—Dylan Thomas (1914–1953)
“There is one, and only one, thing in modern society more hideous than crime—namely, repressive justice.”
—Simone Weil (1909–1943)
“Too poor for a bribe, and too proud to importune,
He had not the method of making a fortune.”
—Thomas Gray (1716–1771)