Clinical decision-making is often fraught with uncertainties. However, expert diagnosticians are able to maintain a degree of suspicion throughout the assessment process, to consider a range of potential explanations, and then to generate and narrow their differential diagnosis, based on their previous experience, familiarity with the evidence related to various diagnoses, and understanding of their individual patient. Through the process, they perform assessment techniques involved in both the history and physical examination in an effective and reliable manner and select appropriate diagnostic studies to support their assessment.