Defining Distinct Negative Beliefs About Uncertainty: Validating the Factor Structure of the Intolerance of Uncertainty Scale

This study examined the factor structure of the English version of the Intolerance of Uncertainty Scale (IUS; French version: M. H. Freeston, J. Rheaume, H. Letarte, M. J. Dugas, & R. Ladouceur, 1994; English version: K. Buhr & M. J. Dugas, 2002) using a substantially larger sample than has been used in previous studies. Nonclinical undergraduate students and adults from the community (M age = 23.74 years, SD = 6.36; 73.0% female and 27.0% male) who participated in 16 studies in the Anxiety Disorders Laboratory at Concordia University in Montreal, Canada were randomly assigned to 2 datasets. Exploratory factor analysis with the 1st sample (n = 1,230) identified 2 factors: the beliefs that uncertainty has negative behavioral and self-referent implications and that uncertainty is unfair and spoils everything. This 2-factor structure provided a good fit to the data (Bentler-Bonett normed fit index = .96, comparative fit index = .97, standardized root-mean residual = .05, root-mean-square error of approximation = .07) upon confirmatory factor analysis with the 2nd sample (n = 1,221). Both factors showed similarly high correlations with pathological worry, and Factor I showed stronger correlations with generalized anxiety disorder analogue status, trait anxiety, somatic anxiety, and depressive symptomatology.