a statistical technique that finds relationships among large quantities of items, like items on an intelligence test. Items that “cluster” are called “factors” and we expect to find certain “clusters” in intelligent people and a lack of these “clusters” or parts to the cluster in less intelligent people.
Average IQ was established by giving thousands of test to thousands of people. The vast majority of 8 yr. olds performed to a certain level on the test, vast majority of 12 yr. olds performed to a certain level…etc. Therefore, that score that the vast majority performed at for an age level became “100”, and therefore an IQ of 100 is considered average.
** Really, now it is no longer a real quotient because scores relate to an Average performance of those of the same age