An intelligence quotient (IQ) is a score derived from one of several standardized tests designed to assess human intelligence. The abbreviation IQ was coined by the psychologist William Stern for the German term Intelligenz-quotient, his term for a scoring method for intelligence tests he advocated in a 1912 book.y this definition, approximately two-thirds of the population scores between IQ 85 and IQ 115, and about 5 percent of the population scores above 125. IQ scores have been shown to be associated with such factors as morbidity and mortality, parental social status, and, to a substantial degree, biological parental IQ.