The Sixteen Personality Factor Questionnaire (16PF), is a self-report personality test developed over several decades of empirical research by Raymond B. Cattell, Maurice Tatsuoka and Herbert Eber. The 16PF provides a measure of normal personality and can also be used by psychologists, and other mental health professionals, as a clinical instrument to help diagnose psychiatric disorders, as well as help with prognosis and therapy planning. The 16PF instrument provides clinicians with a normal-range measurement of anxiety, adjustment, emotional stability and behavioral problems. It can also be used within other areas of psychology, such as career and occupational selection.

Beginning in the 1940s, Cattell used the new statistical technique of common factor analysis which takes as its starting point the matrix of inter-correlations between all the variables (see correlation coefficient) in an attempt to elucidate the underlying source traits of human personality. The 16PF measures 16 primary trait constructs, as well as a version of the Big Five secondary traits, From early on in his research endeavors, Cattell found that personality structure was hierarchical, with both primary and secondary stratum level traits The sixteen primary factors were a result of factor-analyzing multiple clusters of trait synonyms derived from the English-language trait lexicon to elucidate the major underlying dimensions within the normal personality sphere. At the second-stratum, at least five “global” (second-order) factors emerged from factor-analyzing the 16 x 16 intercorrelation matrix for the sixteen primary factors themselves. Thus, the 16PF gives scores on both the five second-order “global” traits (which provide an overview of personality structure at a broader, conceptual level), as well as on the narrower, more-specific primary trait factors, 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.

The measurement of normal personality trait constructs is an integral part of Cattell’s comprehensive theory of intrapersonal psychological variables covering individual differences in cognitive abilities, normal personality traits, abnormal (psychopathological) personality traits, dynamic motivational traits, mood states, and transitory emotional states which are all taken into account in his behavioral specification/prediction equation. The 16PF has also been translated into over 30 languages and dialects and is widely used internationally.

Cattell and his co-workers also constructed downward extensions of the 16PF – parallel personality questionnaires designed to measure corresponding trait constructs in younger age ranges, such as the High School Personality Questionnaire (HSPQ) – now the Adolescent Personality Questionnaire (APQ) for ages 12 to 18 years, the Children’s Personality Questionnaire (CPQ), the Early School Personality Questionnaire (ESPQ), as well as the Preschool Personality Questionnaire (PSPQ).

Cattell also constructed (T-data) tests of cognitive abilities such as the Comprehensive Ability Battery (CAB) – a multidimensional measure of 20 primary cognitive abilities, as well as measures of non-verbal visuo-spatial abilities, such as the three scales of the Culture-Fair Intelligence Test (CFIT), In addition, Cattell and his colleagues constructed objective (T-data) measures of dynamic motivational traits including the Motivation Analysis Test (MAT), the School Motivation Analysis Test (SMAT), as well as the Children’s Motivation Analysis Test (CMAT). As for the mood state domain, Cattell and his colleagues constructed the Eight State Questionnaire (8SQ), a self-report (Q-data) measure of eight clinically important emotional/mood states, labeled Anxiety, Stress, Depression, Regression, Fatigue, Guilt, Extraversion, and Arousal.