A nursing diagnosis follows the assessment phase and involves interpreting assessment data to identify client strengths and problems. It is a standardized statement about a client's health that is used to provide nursing care. The North American Nursing Diagnosis Association helps define standard diagnoses. Creating a nursing diagnosis requires assessment skills, critical thinking, and decision making. A nursing diagnosis has three components: a diagnostic label, etiology, and defining characteristics. A medical diagnosis determines the disease or condition that explains a person's symptoms.