beginning in the 1940s, cattell used several techniques including the new statistical technique of common factor analysis applied to the english-language trait lexicon to elucidate the major underlying dimensions within the normal personality sphere. this method takes as its starting point the matrix of inter-correlations between these variables in an attempt to uncover the underlying source traits of human personality. cattell found that personality structure was hierarchical, with both primary and secondary stratum level traits. at the primary level, the 16pf measures 16 primary trait constructs, with a version of the big five secondary traits at the secondary level. these higher-level factors emerged from factor-analyzing the 16 x 16 intercorrelation matrix for the sixteen primary factors themselves. the 16pf yields scores on primary and second-order "global" traits, thereby allowing a multilevel description of each individual's unique personality profile. a listing of these trait dimensions and their description can be found below. cattell also found a third-stratum of personality organization that comprised just two overarching factors.