National norms for the expanded version of the inventory of depression and anxiety symptoms (IDAS-II).

OBJECTIVES: The present study developed normative data for the expanded version of the Inventory of Depression and Anxiety Symptoms (IDAS-II). The IDAS-II is a self-report measure containing 18 factor-analytically derived scales, each assessing a specific symptom of internalizing disorders, including depression, anxiety disorders, OCD, bipolar disorder, and PTSD. These normative data were used to examine group differences in internalizing symptoms across demographic characteristics.

METHOD: A total of 1,836 Mechanical Turk users (47.6% male; mean age = 35.6) completed the IDAS-II; the sample was weighted to be representative of the U.S. population on gender, age, and race/ethnicity.

RESULTS: Percentiles were derived for each of the IDAS-II scales. Age was the demographic characteristic most consistently associated with lower internalizing symptoms.

CONCLUSIONS: The present study provides information on the distribution of specific internalizing symptoms in a large national sample, as well as on how these symptoms are related to demographic characteristics.