What do Anxiety Scales Really Measure? An Item Content Analysis of Self-Report Measures of Anxiety

Anxiety is a common experience and component of the human condition, but as a construct it is difficult to define and anxiety scales vary in which aspects are emphasized. In the present study, we analyzed and quantified the content overlap of self-report instruments used to measure non-specific or global anxiety. Categorization of the 313 items across thirteen commonly used anxiety scales resulted in 60 disparate categories that spanned a wide variety of symptoms. Mean overlap between all of the selected scales was generally low. On average, only 30.9.% of all symptoms were captured by any given measure. Results indicate that the scales are heterogenous in the content that they measure. Therefore, anxiety-related scales should not be assumed to be interchangeable and careful consideration should be taken when selecting measures.