A comparative validation of the Foulds and Bedford hierarchy of psychiatric symptomatology.

This study investigated the validity of the Fould & Bedford hierarchical model of psychiatric illness, as compared to hierarchical models based upon prevalence and severity of disorder. The DSSI was administered to 52 American psychiatric in-patients with severe disturbances. The reports of symptoms in this sample conformed to the Foulds hierarchy in 90% of cases, while 94% of cases conformed to a model based upon prevalence. When a cross-method validation was investigated, the Foulds & Bedford classification demonstrated good discriminative capacity, while models based upon prevalence and severity failed to achieve significance. These results suggest that the Foulds & Bedford model is a useful taxonomy of symptomatology in psychiatric illness.