Purpose: Designed to assess a unitary factor of depression.
Score: Yields a total score.
Time: (10-20) minutes.
Authors: Samuel Krug and James E. Laughlin.
Publisher: Institute for Personality and Ability Testing.
Description: The developers of the IPAT Depression Scale report that they intended to develop a psychometrically sophisticated measure of depression that could be used with the IPAT Anxiety Scale Questionnaire. This 40-item depression scale was derived from factor analysis of the primary pathology factors of the Clinical Analysis Questionnaire. The authors claimed to have identified a unitary second-order depression factor, after which, they selected items from the item pool that best discriminated the depressive sample from normal and other clinical categories.
Scoring: The number of items endorsed that load for depression are summed and that score is interpreted in relation to suggested cut-off scores.
Reliability: The scale shows an internal consistency (alpha) range from .85 to .94 on various normal and clinical groups.
Validity: Reviewers have suggested that the validity data included in the manual are contaminated by the use of the same subjects employed in item selection. A correlation of .88 was obtained between the scale and the "pure depression factor in a sample of 1,904 normals and clinical cases" which comprised the CAQ norm groups. The correlation between the MMPI D scale and the depression scale is .31.
Norms: The handbook refers to a group of "67 clinically diagnosed depressives" together with 729 other "clinical cases" that were differentially diagnosed against 632 normals. It is not clear how these subjects were selected.
Suggested Uses: Due to the scale’s questionable reliability and validity, reviewers have recommended more extensive research on this measure before endorsing its clinical utility.