Obsessive compulsive symptoms were measured by five items previously used in the Bergen Child Study (Heiervang et al., 2007) that were derived from clinical guidelines developed to identify children and adolescents with OCD (Thomsen, 1998). The symptoms were rated on a 3-point Likert scale with the alternatives ‘not true’, ‘somewhat true’ and ‘definitely true’. The Cronbach's alpha in the current study was 0.71, and none of the items contributed negatively to the alpha value.