however, one big technical difference between cattell's five global factors and popular five-factor models was cattell's insistence on using oblique rotation in the factor analysis whereas goldberg and costa & mccrae used orthogonal rotation in their factor analysis. oblique rotation allows the factors to correlate with each other, whereas orthogonal rotation restricts the factors from correlating with each other. although personality traits are thought to be correlated, using orthogonal factor analysis makes the factors easier to understand and to work on statistically in research. this is one of the reasons the big-five traits have definitions that are different from the 16pf global factors. for example, as seen in the table below, in cattell's model the primary personality trait of dominance (factor e) is strongly located in the independence/accommodation global factor which represents a quality of fearless, original thinking and forceful, independent actions. however, other popular big five models consider dominance as a facet of several big-five traits, including extraversion, dis-agreeableness, and conscientiousness. thus dominance is spread across a range of big-five factors with little influence on any one (cattell & mead, 2008). below is a table that shows how the 16 primary factors are related to the five global factors of the 16 personality factor theory. compare with the hierarchical structure of the big five. also, note that factor b is considered separate from the other factors because it is not a part of the hierarchical structure of personality in the same way as the other factors.