Factor analysis
The development of factor analysis as a popular statistical technique in differential psychology has led to an increase in attempts at finding underlying traits. More recently this has been used in the context of personality disorders both as a means of looking at which personality traits current categorical diagnoses are related to and also as a method of looking for new psychopathological latent variables. Factor analysis has helped illustrate that the full range of relevant personality pathology is not included in the DSM psychiatry nosology. However the technique does not show information about a continuum from normal to clinically relevant personality.