Categorical models of classification appear to be easier to use. Dimensional models are inherently more complex because they generally provide more specific and precise information.

Ease of usage I

Dimensional models could be easier to use because it provides a more valid and internally consistent means to describe a particular patient's psychopathology. 

A dimensional model might be less cumbersome because it would not require the assessment of numerous diagnostic criteria from overlapping categories to make illusory distinctions. 

Ease of usage II 

NOS is generally used when a clinician has determined that a mental disorder is present, but the person fails to meet the criteria for one of the existing diagnostic categories. 

Not otherwise specified (NOS)

There is currently no consistently applied or well-understood threshold for the presence of a categorical diagnosis. 

Threshold for mental disorder diagnoses

Clinical utility is the extent to which DSM assists clinical decision makers in fulfilling the various clinical functions of a psychiatric classification.

University of Illinois at Urbana-Champaign

Dilemmas of the categorical model

Research on categorical versus dimensional models

Clinical utility

Categorical or Dimensional

Mullins-Sweatt, S. N., & Widiger, T. A. (2009). Clinical utility and DSM-V. Psychological Assessment, 21(3), 302. https://doi.org/10.1037/a0016607

Clinical Utility and DSM–V

Clinical utility

Categorical classification divides mental disorders into types based on criterion sets with defining features. Researchers and clinicians following this model would diagnose and conceptualize conditions of disorders as qualitatively distinct from normal functioning and from one another. 

Categorical classification

A dimensional system classifies clinical presentations based on quantification of attributes rather than the assignment to categories and works best in describing phenomena that are distributed continuously and that do not have clear boundaries. 

Dimensional classification

Excessive diagnostic co-occurrence

Boundary disputes

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