“…Principal Component analysis was originally developed by Pearson (1901) and further improved by Hotelling (1933). As to the literature on factor analysis, see, among others Agénor, 2003; Andersen and Herbertsson, 2003;DeVellis, 2003;Dien et al, 2005;Finch, 2006;Hambleton et al, 1991; Heshmati and Oh, 2007;Heshmati et al, 2008; Heshmati, 2006a;Kang, 2002;Kieffer, 1998;McDonald, 1997;McLeod et al, 2001. Promax factor analysis emerges as the most suitable method.…”