Intolerance of Uncertainty Test (IUS-12)

Carleton, Norton and Asmundson published the IUS-12 in 2007 in the Journal of Anxiety Disorders. Intolerance of uncertainty is the tendency to see the possibility of a negative event as unacceptable, however likely it is. The authors describe it as a key component of worry, state anxiety and related anxiety problems.

The IUS-12 is a short form of the 27-item Intolerance of Uncertainty Scale that Freeston and colleagues introduced in 1994. Studies of the longer scale had found four-factor and five-factor structures, and its items overlapped a lot. The authors tested a reduced version in two undergraduate samples and kept 12 items in two factors.

In the 2007 study, the 12-item version kept what the authors called exemplary internal consistency. It correlated extremely well with the 27-item scale and with measures of anxiety and worry, and it showed a stable two-factor structure. Prospective anxiety covers the desire for predictability, anxiety about future events and active information seeking. Inhibitory anxiety covers avoidance and freezing in the face of uncertainty.

Later studies found one strong general factor. In 663 undergraduates (387 women and 276 men), a model with one general factor plus the two subscale factors fit better than a two-factor model. The general factor also accounted for more common variance than either subscale. In a study of 136 people with generalized anxiety disorder and 76 without, the authors concluded that for people with the disorder only the total score carries a meaningful interpretation.

The authors' abstract gives no cut-offs, and we found no official ones. In that same study of generalized anxiety disorder, a cut-off of 28 best separated people with the disorder from people without it. A 2012 analysis of 977 people found that intolerance of uncertainty is dimensional, so there's no natural dividing line. The sample included anxiety disorder outpatients and community residents. A 2023 paper cites average totals of 25.85 (SD 9.45) in studies of undergraduates and the general population. It cites 37.49 (SD 11.40) for people seeking treatment.

The IUS-12 has no official cut-offs, and the authors' group found that intolerance of uncertainty is dimensional. The 24 and 40 on our page are conventions. A person near the student average and a person near the treatment-seeking average both land in our Moderate band.

The original samples were undergraduates, and later papers describe such samples as young, mostly female and low on average IUS scores. The longer scale was built from clinical judgment, and some of its items appear specific to generalized anxiety disorder. The short form removed some redundant and GAD-specific items.

The IUS-12 measures how you respond to uncertainty. It doesn't measure how much uncertainty you're facing now. Higher scores go with several problems, including generalized anxiety, OCD, social anxiety, panic and health anxiety. A high score therefore doesn't point to one condition, and it isn't a diagnosis.

Take it again after a few weeks if you're working on how you handle not knowing. We found no published figure for how many points make a real change. Look for a clear trend over a few tries rather than one jump. See a doctor or therapist if worry about uncertain things keeps you from deciding, acting or sleeping. The same goes for checking again and again for reassurance.

Our page on intolerance of uncertainty explains the idea. Worry time and "what if" thoughts cover two ways people work with it.

More on this topic: Intolerance of uncertainty, Worry time, "What if" thoughts, Anxiety test (GAD-7).

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• Carleton, Norton and Asmundson, 2007, Journal of Anxiety Disorders (PubMed): Abstract only (the full text is paywalled). Supports the derivation from the 27-item scale, the two undergraduate samples, the two factors and the authors' description of internal consistency.
• Jacoby et al., 2013, Journal of Anxiety Disorders (author copy, UNC): Describes the IUS-12 as a short form of the 27-item scale, the 1 to 5 scoring, the two factors (7 and 5 items), the limits of the 27-item scale and links to other anxiety problems.
• Freeston et al., 1994, Personality and Individual Differences (DOI record): Bibliographic record for the 27-item scale, checked through Crossref. We didn't read the article itself.
• Huntley et al., University of Liverpool repository (author accepted manuscript): Item-to-factor table (prospective 1, 2, 4, 5, 8, 9, 11; inhibitory 3, 6, 7, 10, 12), subscale ranges of 7 to 35 and 5 to 25, and removal of GAD-specific items. UK student samples.
• Hale et al., 2016, Journal of Personality Assessment (PubMed): Abstract only. 387 women and 276 men; bifactor model fit best, with a strong general factor.
• Wilson et al., 2020, Journal of Anxiety Disorders (PubMed): Abstract only. 136 people with generalized anxiety disorder and 76 without; cut-off of 28; only the total score supported.
• Carleton et al., 2012, Journal of Anxiety Disorders (PubMed): Abstract only. Taxometric analysis of 977 people found a dimensional structure.
• Kusec et al., 2023, Assessment (PMC): Source of the cited averages of 25.85 and 37.49. The paper attributes them to earlier work, which we couldn't check.