title: Bifactor structure of the schizotypal personality questionnaire (SPQ).
abstract: The schizotypal personality questionnaire (SPQ) is used to characterize schizotypy, a complex construct helpful for the investigation of schizophrenia-related psychopathology and putative endophenotypes. The SPQ factor structure at item level has been rarely replicated and no study had tested a bifactor model of the SPQ so far. The unidimensional, the correlated, the second-order and the bifactor models of the SPQ were tested to evaluate whether the items converge into a major single factor defining the schizotypy-proneness of the participants, to be used for grouping purpose. Parallel principal component analysis (PCA) and confirmatory factor analysis (CFA) were used to determine the optimal number of factors and components in a cross-sectional, survey design involving 649 college students (males: 47%). The first-order, nine-subscale model was confirmed by CFA in the whole sample. The best evidence from parallel PCA in the training set was in favor of a two-factor model; the bifactor implementation of this model showed good fit in the subsequent CFA. Two main dimensions of positive and negative symptoms underlie schizotypy in non-clinical samples, entailing specific risk of psychosis. On a measurement level, the study provided support for the use of the total scores of the SPQ to characterize schizotypy.
authors.affiliation: Center of Liaison Psychiatry and Psychosomatics, University Hospital, University of Cagliari, Cagliari, Italy; Section on Clinical Psychology, Department of Education, Psychology, Philosophy, University of Cagliari, Cagliari, Italy; Genneruxi Medical Center, Cagliari, Italy. Electronic address: apreti@tin.it.
authors.forename: Antonio
authors.initials: A
authors.lastname: Preti
authors.affiliation: Section on Clinical Psychology, Department of Education, Psychology, Philosophy, University of Cagliari, Cagliari, Italy; Unit of Research and development, Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Siddi
authors.affiliation: Center of Liaison Psychiatry and Psychosomatics, University Hospital, University of Cagliari, Cagliari, Italy.
authors.forename: Marcello
authors.initials: M
authors.lastname: Vellante
authors.affiliation: Section on Clinical Psychology, Department of Education, Psychology, Philosophy, University of Cagliari, Cagliari, Italy.
authors.forename: Rosanna
authors.initials: R
authors.lastname: Scanu
authors.affiliation: Section on Clinical Psychology, Department of Education, Psychology, Philosophy, University of Cagliari, Cagliari, Italy.
authors.forename: Tamara
authors.initials: T
authors.lastname: Muratore
authors.affiliation: Section on Clinical Psychology, Department of Education, Psychology, Philosophy, University of Cagliari, Cagliari, Italy.
authors.forename: Mersia
authors.initials: M
authors.lastname: Gabrielli
authors.affiliation: Section on Clinical Psychology, Department of Education, Psychology, Philosophy, University of Cagliari, Cagliari, Italy.
authors.forename: Debora
authors.initials: D
authors.lastname: Tronci
authors.affiliation: Section on Clinical Psychology, Department of Education, Psychology, Philosophy, University of Cagliari, Cagliari, Italy.
authors.forename: Carmelo
authors.initials: C
authors.lastname: Masala
authors.affiliation: Section on Clinical Psychology, Department of Education, Psychology, Philosophy, University of Cagliari, Cagliari, Italy.
authors.forename: Donatella Rita
authors.initials: DR
authors.lastname: Petretto
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D058068:Endophenotypes; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008960:Models, Psychological; D010551:Personality; D010555:Personality Inventory / Q000706:statistics & numerical data; D011594:Psychometrics / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D012569:Schizotypal Personality Disorder / Q000175:diagnosis*; D013334:Students; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Confirmatory factor analysis; Early Intervention; Psychosis; Schizophrenia; Schizotypal Personality Questionnaire; Schizotypy