Testing a tripartite model: I. Evaluating the convergent and discriminant validity of anxiety and depression symptom scales.

L.A. Clark and D. Watson (1991) proposed a tripartite model that groups symptoms of depression and anxiety into 3 subtypes: symptoms of general distress that are largely nonspecific, manifestations of somatic tension and arousal that are relatively unique to anxiety, and symptoms of anhedonia and low Positive Affect that are specific to depression. This model was tested in 5 samples (3 student, 1 adult, and 1 patient sample) using the Mood and Anxiety Symptom Questionnaire (MASQ; D. Watson & L. A. Clark, 1991), which was designed to assess the hypothesized symptom groups, together with other symptom and cognition measures. Consistent with the tripartite model, the MASQ Anxious Arousal and Anhedonic Depression scales both differentiated anxiety and depression well and also showed excellent convergent validity. Thus, differentiation of these constructs can be improved by focusing on symptoms that are relatively unique to each.