Clarifying the Factor structure of the Intolerance of Uncertainty Inventory: Measurement Invariance and Validity in Predicting Clinical Outcomes

Abstract The Intolerance of Uncertainty Inventory (IUI) is a two-part inventory assessing the general unacceptability uncertainty in terms generalized maladaptive beliefs (IUI-A) and specific individuals’ reactions to uncertainty, such as avoidance, doubt, overestimation threat, worry, control seeking reassurance (IUI-B). Previous research has examined factor structure both parts with mixed results, especially for IUI-A. present study took advantage Farsi-language version clarify IUI structure, assess measurement invariance between clinical nonclinical samples, examine criterion-related incremental validity IUI-A IUI-B. We administered psychiatric sample patients who met DSM-IV criteria affective disorders ( N = 198) community participants relatively good health 427). Exploratory structural equation modeling analyses were used test alternative models determine whether factors predicted depression anxiety symptoms. A bifactor model was found be best fit IUI-B, reliability supported use total scores parts. IUI-B scalar invariant. each part worry higher than participants. Validity showed that two tapped into same variance symptoms competing instruments, although not superior predictive performance scale (IUS-12) Disorder Specific (DSIU) scale. clarified factorial provided evidence are reliable valid construct predicting outcomes.