VI.—The Estimation of Factor Loadings by the Method of Maximum Likelihood

When a battery of intelligence tests is administered to a set of persons it is a common practice among psychologists to “explain” the scores obtained in terms of a number of “factors.” Thus if we suppose that there are altogether t tests and that x i , denotes the score of any one person in the i th test, then it is assumed that where f, g , …, h represent the person's measures in one or more general or group factors, and S i , is the person's specific ability in the i th test. It is further assumed that for a given and supposed infinite population of persons all the factors, specific and otherwise, are distributed normally and independently and that they are standardised, i.e. that their standard deviations are unity.