Determining the cause or causes of a congenital defect, injury or illness and accounting for its symptoms and signs. Diagnosis implies that a causative mechanism for the condition is known. Three broad categories of diagnosis can be identified: clinical diagnosis (based on signs and) symptoms, diagnosis by exclusion (ruling out all but one disease thought to be the determinant), and differential diagnosis (identifying which of two or more diseases with similar signs or symptoms is the determinant).
See Bayley Scales of Infant and Toddler Development, Causal pathway, Clinical neuropsychology, Co-morbidity, Development delay, Developmental screening, IDEA, Likelihood ratio (LR), Pathogenesis (or pathogeny) Pathophysiology, Psychopathology, Prognosis, Signs and symptoms