The Intelligence, IQ, and g are different. The Intelligence is the word used in ordinary discourse to known as the cognitive ability. On the other hand, it is normally regarded as too inaccurate to be useful for a scientific treatment of the subject. The intelligence quotient (IQ) is an index considered from the scores on test items evaluated by experts to take in the abilities covered by the word intelligence. The IQ measures a multidimensional quantity: it is a combination of different kinds of abilities, the proportions of which probably will differ between IQ tests. The dimensionality of IQ scores can be considered by the factor analysis, which reveals a single main factor basic the scores on all IQ tests. This thing, which is a hypothetical construct, is called g. Variation in g corresponds directly to the intuitive notion of intelligence, and therefore g is at times called general cognitive ability or the general intelligence.