title: Secondary Psychometric Examination of the Dimensional Obsessive-Compulsive Scale: Classical Testing, Item Response Theory, and Differential Item Functioning.
abstract: The Dimensional Obsessive-Compulsive Scale (DOCS) is a promising measure of obsessive-compulsive disorder (OCD) symptoms but has received minimal psychometric attention. We evaluated the utility and reliability of DOCS scores. The study included 832 students and 300 patients with OCD. Confirmatory factor analysis supported the originally proposed four-factor structure. DOCS total and subscale scores exhibited good to excellent internal consistency in both samples (α = .82 to α = .96). Patient DOCS total scores reduced substantially during treatment (t = 16.01, d = 1.02). DOCS total scores discriminated between students and patients (sensitivity = 0.76, 1 - specificity = 0.23). The measure did not exhibit gender-based differential item functioning as tested by Mantel-Haenszel chi-square tests. Expected response options for each item were plotted as a function of item response theory and demonstrated that DOCS scores incrementally discriminate OCD symptoms ranging from low to extremely high severity. Incremental differences in DOCS scores appear to represent unbiased and reliable differences in true OCD symptom severity.
authors.affiliation: University of Regina, Regina, Saskatchewan, Canada mikethibodeau@gmail.com.
authors.forename: Michel A
authors.initials: MA
authors.lastname: Thibodeau
authors.affiliation: Rogers Memorial Hospital, Oconomowoc, WI, USA.
authors.forename: Rachel C
authors.initials: RC
authors.lastname: Leonard
authors.affiliation: University of North Carolina at Chapel Hill, NC, USA.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Abramowitz
authors.affiliation: Rogers Memorial Hospital, Oconomowoc, WI, USA.
authors.forename: Bradley C
authors.initials: BC
authors.lastname: Riemann
mesh_terms: D000328:Adult; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D009771:Obsessive-Compulsive Disorder / Q000523:psychology*; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Dimensional Obsessive-Compulsive Scale; differential item functioning; item response theory; obsessive-compulsive disorder; psychometric analyses