ABSTRACT
The aim was to evaluate the validity and reliability of the persian version of Yale-Brown Obsessive- Compulsive Scale [Y-BOCS]. The sum of 140 patients with obsessive-compulsive disorder [OCD] and 30 individual participants without OCD were selected via convenient sampling as experimental and control groups respectively. Data gathering was done using Y-BOCS, Structured Clinical Interview for DSM-IV axis-I disorders [SCID-I] and Symptom Checklist-90-Revised Obsessive-Compulsive Symptoms [SCL-90-R-OCS]. Reliability coefficients were calculated by Cronbach's alpha, split-half, and test-retest reliability. For validity assessment, concurrent criterion-related validity in correlation with SCID-I and SCL-90-R-OCS, and construct validity [exploratory factor analysis] were executed. In order to normalize the Y-BOCS after insuring that the distribution is normal and does not have kurtosis and skewness, mean and standard deviation were used as the most appropriate central tendencies and deviation. Optimal levels of internal consistency scores [symptom checklist 0.97, severity scale 0.95] split-half reliability [symptom checklist 0.93, severity scale 0.89], and test-retest reliability [0.99] were calculated. Concurrent reliability were examined and established by correlating the Y-BOCS with the SCL-90-R-OCS and SCID-I. Exploratory factor analysis was also examined, which indicated three factors for symptom checklist scale and two factors for symptom severity scale. Cutoff point value [9] was also determined. The results supported satisfactory validity and reliability of translated form of Yale-brown Obsessive-Compulsive Scale for research and clinical diagnostic applications