title: Subscale structure for the Positive and Negative Syndrome Scale (PANSS): a proposed solution focused on clinical validity.
abstract: Although the items of the Positive and Negative Syndrome Scale (PANSS) are ordinal, continuous data methods are consistently used to analyze them. The current study addresses this issue by applying a categorical method and critically examining the ideas of item inclusion and goodness of fit. Data from 1527 subjects were used to test a proposed solution to the factor structure of the PANSS using a categorical factor analytic method. The model was made more generalizable by setting a minimum level of association between the item and the factor, and the results were then compared to existing solutions. The model was also tested for consistency in a first-episode sample. Use of categorical methods indicated similar results to previous analyses; however, it is demonstrated that the strength of the estimates can be unstable when items are shared across factors. The current study demonstrates that solutions can change substantially when a model is over-fitted, and therefore use of measures of fit as the criterion for an acceptable model can mask important relationships and decrease clinical validity.
authors.affiliation: Department of Biostatistics and Bioinformatics, Emory University, Rollins School of Public Health, 1518 Clifton Road NE, Atlanta, GA 30329, USA. mekelle@emory.edu
authors.forename: Mary E
authors.initials: ME
authors.lastname: Kelley
authors.forename: Leonard
authors.initials: L
authors.lastname: White
authors.forename: Michael T
authors.initials: MT
authors.lastname: Compton
authors.forename: Philip D
authors.initials: PD
authors.lastname: Harvey
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics / Q000295:instrumentation; D015203:Reproducibility of Results; D012559:Schizophrenia / Q000175:diagnosis*; D012565:Schizophrenic Psychology; D055815:Young Adult