Development and Validation of the Inventory of Depression and Anxiety Symptoms (IDAS)

David Watson, University of Iowa
Michael W. O'Hara, University of Iowa
Leonard J. Simms
Roman Kotov
Michael Chmielewski, University of Iowa
Elizabeth A. McDade-Montez, University of Iowa
Wakiza Gamez, University of Iowa
Scott Stuart, University of Iowa

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Published in Psychological Assessment, 19:3 (2007) pp. 253-268. DOI: 10.1037/1040-3590.19.3.253 Copyright © 2007 American Psychological Association. Used by permission. http://www.apa.org/journals/pas/

This article may not exactly replicate the final version published in the journal. It is not the copy of record.

Abstract

We describe a new self-report instrument, the Inventory of Depression and Anxiety Symptoms (IDAS), which was designed to assess specific symptom dimensions related to major depression and related anxiety disorders. We created the IDAS by conducting principal factor analyses in three large samples (college students, psychiatric patients, community adults); we also examined the robustness of its psychometric properties in five additional samples (high school students, college students, young adults, postpartum women, psychiatric patients) that were not involved in the scale development process. The IDAS contains 10 specific symptom scales: Suicidality, Lassitude, Insomnia, Appetite Loss, Appetite Gain, Ill Temper, Well-Being, Panic, Social Anxiety, and Traumatic Intrusions. It also includes two broader scales: General Depression (which contains items overlapping with several other IDAS scales) and Dysphoria (which does not). The scales (a) are internally consistent, (b) capture the target dimensions well, and (c) define a single underlying factor. They show strong short-term stability, and display excellent convergent validity and good discriminant validity in relation to other self-report and interview-based measures of depression and anxiety.