Longitudinal construct validity of Brief Symptom Inventory subscales in schizophrenia.
Longitudinal validity of Brief Symptom Inventory subscales was examined in a sample (N = 318) with schizophrenia-related illness measured at baseline and every 6 months for 3 years. Nonlinear factor analysis of items was used to test graded response models (GRMs) for subscales in isolation. The models varied in their within-time and between-times parameter constraints, with the homogeneous model being the least constrained, followed by the 2-parameter GRM and 1-parameter GRM. Results show that 4 subscales (Interpersonal Sensitivity, Hostility, Paranoid Ideation, Psychoticism) were consistent with the 1-parameter GRM, and 5 subscales (Somatization, Obsessive-Compulsive, Depression, Anxiety, Phobic Anxiety) were consistent with the 2-parameter GRM. There is evidence that the 9 subscales may be validly used to study change in single constructs over time.
Long
Jeffrey D
JD
Department of Educational Psychology, Quantitative Methods in Education, University of Minnesota-Twin Cities, 178 Pillsbury Drive SE, Minneapolis, MN 55455, USA. longj@umn.edu
Harring
Jeffrey R
JR
Brekke
John S
JS
Test
Mary Ann
MA
Greenberg
Jan
J
D000328:Adult; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008960:Models, Psychological; D015203:Reproducibility of Results; D012559:Schizophrenia / Q000175:diagnosis*; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires