The Anxiety Depression Distress Inventory-27 (ADDI-27): New Evidence of Factor Structure, Item-Level Measurement Invariance, and Validity.

Three studies examining the factor structure and psychometric properties of the Anxiety Depression Distress Inventory-27 (ADDI-27) extended the initial instrument development studies for this recently introduced inventory. The ADDI-27 is an empirically derived short form of the Mood and Anxiety Questionaire-90 (MASQ-90) comprising three scales: Positive Affect, Somatic Anxiety, and General Distress. The main objectives of Study 1 (N = 700) were to examine the factor structure of the ADDI-27 and its measurement invariance across gender at the item level. The objective of Study 2 (N = 538) was to examine evidence for the convergent and discriminant validity of scores on the ADDI-27. The objective of Study 3 (N = 240) was to assess further evidence for the nomological network and convergent and discriminant validity of the ADDI-27 scores. Results of exploratory structural equation modeling yielded strong support for a 3-factor model, with approximate fit indexes meeting or exceeding the conventional cutoffs. With p ≤ .001 as the criterion for detecting noninvariance, results of measurement invariance analysis suggested that all of the ADDI-27 items were invariant across gender. Results of multivariate validity analyses across 2 studies provided support for the convergent and discriminant validity of scores on the ADDI-27 scales.