originally iq was defined as
intelligence quotient (IQ). defined originally as the ratio of mental age (ma) to chronological age (ca) multiplied by 100 [thus, IQ = (ma/ca) x 100]. On contemporary intelligence tests, the average performance for a given age is assigned a score of 100.efined originally as the ratio of mental age (ma) to chronological age (ca) multiplied by 100 [thus, IQ = (ma/ca) x 100]. On contemporary intelligence tests, the average performance for a given age is assigned a score of 100.