Any unexplained phenomenon passes through three stages before the reality of it is accepted. During the first stage it is considered laughable. During the second stage, it is adamantly opposed. Finally, during the third stage, it is accepted as self-evident. - Arthur Schopenhauer
Depression assessment scales come in two basic forms - interviewer/clinician rated and sufferer/patient rated. As stated in the background information on the IDS/QIDS questionnaires (see below) "There are several accepted clinician rated and patient self report measures of depressive symptoms. The most commonly used clinician rated scales are the 17, 21, 24, 28, and 31 item versions of the Hamilton Rating Scale for Depression (HRSD) (Hamilton 1960, 1967), and the 10-item Montgomery-Asberg Scale (Montgomery and Asberg 1979). The most frequently used self-reports include the 13, and 21 item version of the Beck Depression Inventory (BDI) (Beck et al. 1961), the BDI-II (Beck et al. 1996), the Zung Depression Rating Scale (Zung 1965), the Carroll Rating Scale (CRS) (Carroll et al. 1981), and the Patient Health Questionnaire - 9 (PHQ-9) (Kroenke et al.