Clinical findings include observations experienced by patients, caretakers, and health care professionals. The key aspect of "clinical" is that it requires a human being to verbalize a sensation, perception, or observation. Once the verbage is converted into a standard medical terminology, it can be treated in a manner analogous to other medical test results and used for diagnosis. Although most health care professionals may disagree with the analogy, symptoms, signs and lab tests are mathematically equivalent in a diagnostic sense.

A symptom is a mental or physical effect experienced by a patient and reported by the patient, or by a caretaker if the patient is unable to communicate the effect. A health care professional elicits symptoms by taking a careful medical history usually triggered by a chief complaint or complaints or a traumatic event. Most symptoms are quantified as being absent or present.

A sign is a physical effect observed or measured by a health care professional. A physical examination is used to assess the patient's clinical condition. The examination includes inspection, palpation, percussion, ausculatation, measurement , and manipulation, These are quantified as absent or present, positive or negative, degree of abnormality, and numerical values.

The Argo diagnostic software was developed to use laboratory test results to find the shortest list of clinical diagnoses (differential diagnosis). From a mathematical standpoint, symptoms and signs are equivalent to laboratory tests except most of the effects are quantified by a health care professional instead of an analytical instrument.