Lewis Terman, developer of the Stanford-Binet Intelligence Scales, based his English-language Stanford-Binet IQ test on the French-language Binet-Simon test developed by Alfred Binet. Terman believed his test measured the "general intelligence" construct advocated by Charles Spearman (1904).[48][49] Terman differed from Binet in reporting scores on his test in the form of intelligence quotient ("mental age" divided by chronological age) scores after the 1912 suggestion of German psychologist William Stern. Terman chose the category names for score levels on the Stanford-Binet test. When he first chose classification for score levels, he relied partly on the usage of earlier authors who wrote, before the existence of IQ tests, on topics such as individuals unable to care for themselves in independent adult life. Terman's first version of the Stanford-Binet was based on norming samples that included only white, American-born subjects, mostly from California, Nevada, and Oregon.