- Degree of overdetermination of the factor (or number of factors/number of variables)
- Overdetermination is the factor-to-variable ratio (Preacher & MacCallum, 2002).
- Six or seven indicators per factor and a rather small number of factors is considered as high overdetermination of factors if many or all communalities are under .50 (MacCallum, Widaman, Zhang, & Hong, 1999).
- A minimum of 3 variables per factor is critical. This confirms the theoretical results of T. W. Anderson and Rubin (1956; also see McDonald & Krane, 1977, 1979, and Rindskopf, 1984). (Velicer, & Fava, 1998, p. 243).
- At least four measured variables for each common factor and perhaps as many as six (Fabrigar, Wegener, MacCallum, & Strahan, 1999, p. 282)
- A factor with fewer than three itmes is generally weak and unstable (Costello & Osborne, 2005, p. 5)