Multiple studies investigating the validity of the tripartite model or affect in youth have been supportive of the model; however, few studies have examined the model in narrow age bands or large clinical samples. The current study examined the structure of affect in a sample of psychiatrically hospitalized adolescents. Structural equation modeling was used to examine two-factor (negative affectivity [NA] and positive affectivity [PA]) and three-factor models (NA, PA, and physiological hyperarousal [PH]) with item level data from the Reynolds Adolescent Depression Scale (RADS) and Revised Children's Manifest Anxiety Scale (RCMAS), and from the Millon Adolescent Clinical Inventory (MACI), RADS, and RCMAS. Analyses were completed for the overall sample and for depressive, anxiety, comorbid depression, and anxiety, and other diagnostic groups.

With data from the RADS and RCMAS, both the two- and three-factor models provided an equally good fit to the data for the overall sample. However, when tested for invariance across diagnostic groups, the two-factor model was invariant across groups, while the three-factor model yielded inadmissible solutions for the comorbid group, suggesting the two-factor solution provided the best fit to the data. For the data from the MACI, RADS, and RCMAS, one-, two-, and three factor models were tested, but it was not possible to identify a model of acceptable fit.

The t tests were used to examine the patterns of construct scores across diagnostic groups to determine if they were consistent with the tripartite model. Using data from the RCMAS and the RADS, the depressive and anxious diagnostic groups demonstrated similarly high levels of NA, while the anxious group demonstrated significantly higher levels of PA than the depressive group. Similar analyses could not be completed for the data from the MACI, RADS, and RCMAS because of the small sample size for the anxious diagnostic group.

While the results of SEM and t-test analyses demonstrate support for the tripartite model and the associated constructs of NA and PA, support was not demonstrated for PH. Results suggest that the tripartite model may be dependent on the instruments used to assess it. Limitations of this study and implications and directions for future research are discussed.