Yale-Brown Obsessive Compulsive Scale (Y-BOCS)

The Yale-Brown Obsessive Compulsive Scale (Y-BOCS) is a 10-item scale designed to measure the severity and type of symptoms in people with obsessive-compulsive disorder (OCD) over the past seven days. The symptoms assessed are obsessions and compulsions. This scale is useful in tracking OCD symptoms at intake and during/after treatment.
This scale was validated by Goodman et al. (1989b) who found that the Y-BOCS was significantly correlated with two independent measures of OCD. The same study also showed that the Y-BOCS is sensitive to changes in OCD symptoms. The Y-BOCS also has high internal consistency and high interrater reliability (Goodman et al., 1989a).

Total Y-BOCS scores range from 0 to 40, with higher scores indicating greater severity of OCD symptoms. Scores on the obsession and compulsion subscales range from 0 to 20, but only the total Y-BOCS score is interpreted. Total scores can be split into five categories, based on severity of symptoms.

People who have a total Y-BOCS score:

Under 7 are likely to be subclinical,
8-15 are likely to have a mild case of OCD,
16-23 are likely to have a moderate case of OCD,
24-31 are likely to have a severe case of OCD,
32-40 are likely to have an extreme case of OCD.

Goodman, W. K., Price, L. H., Rasmussen, S. A., Mazure, C., Fleischmann, R. L., Hill, C. L., … Charney, D. S. (1989a). The Yale-Brown Obsessive-Compulsive Scale. I. Development, Use, and Reliability. Archives of General Psychiatry, 46(11), 1006-1011.