title: Kinds versus continua: a review of psychometric approaches to uncover the structure of psychiatric constructs.
abstract: The question of whether psychopathology constructs are discrete kinds or continuous dimensions represents an important issue in clinical psychology and psychiatry. The present paper reviews psychometric modelling approaches that can be used to investigate this question through the application of statistical models. The relation between constructs and indicator variables in models with categorical and continuous latent variables is discussed, as are techniques specifically designed to address the distinction between latent categories as opposed to continua (taxometrics). In addition, we examine latent variable models that allow latent structures to have both continuous and categorical characteristics, such as factor mixture models and grade-of-membership models. Finally, we discuss recent alternative approaches based on network analysis and dynamical systems theory, which entail that the structure of constructs may be continuous for some individuals but categorical for others. Our evaluation of the psychometric literature shows that the kinds-continua distinction is considerably more subtle than is often presupposed in research; in particular, the hypotheses of kinds and continua are not mutually exclusive or exhaustive. We discuss opportunities to go beyond current research on the issue by using dynamical systems models, intra-individual time series and experimental manipulations.
authors.affiliation: Department of Psychology,University of Amsterdam,Weesperplein 4,Amsterdam 1018 XA,The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: Borsboom
authors.affiliation: Department of Psychology,University of Amsterdam,Weesperplein 4,Amsterdam 1018 XA,The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Rhemtulla
authors.affiliation: Department of Psychology,University of Amsterdam,Weesperplein 4,Amsterdam 1018 XA,The Netherlands.
authors.forename: A O J
authors.initials: AO
authors.lastname: Cramer
authors.affiliation: Department of Psychology,University of Amsterdam,Weesperplein 4,Amsterdam 1018 XA,The Netherlands.
authors.forename: H L J
authors.initials: HL
authors.lastname: van der Maas
authors.affiliation: Department of Aquatic Ecology and Water Quality Management,Wageningen University,6700 AA Wageningen,The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Scheffer
authors.affiliation: Department of Biological Psychology,VU University,1081 BT Amsterdam,The Netherlands.
authors.forename: C V
authors.initials: CV
authors.lastname: Dolan
mesh_terms: D006801:Humans; D001523:Mental Disorders / Q000145:classification*; D008960:Models, Psychological; D011594:Psychometrics
keywords: Dynamical systems; latent variable models; network models; psychometrics; taximetrics