See common variance. The eigenvalues are plotted in the sequence of the principal factors. The number of factors is chosen where the plot levels off to a linear decreasing pattern. The figure below suggests a two-factor solution, since the eigenvalues begin a linear decline commencing with the third factor. See main diagonal.
Unique variance is composed of specific and error variance.
See common, specific and error variance. See common variance. Varimax is the most common rotational criterion.