ABSTRACT
Charles Spearman is credited with the early development of factor analysis. He studied the correlations between students’ test scores of various types and noted that many observed correlations could be accounted for by a simple model (Spearman, 1904). For example, in one case, he obtained the matrix of correlations shown in Table 7.1 for how boys in a preparatory school scored on tests in Classics, French, English, mathematics, discrimination of pitch, and music. He noted that this matrix has the interesting property that any two rows are almost proportional if the diagonals are ignored. Thus, for rows Classics and English, there are the ratios
0 83 0 67
0 70 0 64
0 66 0 54
0 63 0 51
1 2 . .
