The full form of IQ is Intelligence Quotient. IQ is a composite score derived from several standardized tests or subtests designed to measure an individuals level of intelligence. The term "IQ" was coined by psychologist William Stern for the German term "Intelligenzquotient," which he proposed in a book published in 1912 for a rating system for IQ tests at the University of Breslau. The IQ score represents the relative level of intelligence of an individual. One of the many standardized test designs for acquiring human information can be used to determine a persons IQ. The standardizing IQ sample can be defined as IQ 100, and the deviation up and down is fixed at 15 IQ points. According to one survey, two-thirds of the population has an IQ between 85 and 115, and just 5% of people have 125 scores.