For clinical purposes the validity of diagnoses rests almost entirely with prognosis and therapeutics. That is, does making a diagnosis allow improved prediction about course and outcome, or responsiveness to various therapeutic interventions? Insofar as DSM is primarily a guide for practitioners—and only secondarily for researchers—any advances should improve prognosis and therapeutic choice. This viewpoint is not consistently followed in Advancing DSM. For example, the introduction states: "Problems with DSM-IV are faced every day by clinicians (problems such as the high frequency of comorbidity or the intellectual incoherence of axis II)." Those are not major concerns for clinicians, although they do present problems to nosologists. As the editors state, "An accurate diagnosis is a foundation for selecting the best treatment, determining prognosis, and enhancing understanding of the patients."