I have pushed this slightly further to include a small amount of formal clinical decision analysis, including revision of probability. I believe this content is appropriate to this course. I would appreciate your feedback at the end of the course. We look at the sensitivity and specificity of the test. Sensitivity is the chance that a positive test will detect all cases of the disease.
Most tests yield a continuum of values, and a threshold is set for positive or negative.
Where this threshold is set determines whether the test will be highly sensitive or highly specific. The prior probability of disease is the chance of disease before the test is ordered. If we don't know anything about the patient, the probability of disease is the incidence in the general population. My message to the students is that a thoughtful history and physical examination along with an understanding of pathophysiology will make for much better medicine than going straight to technology. The prior probability is important because these rates have to be multiplied by the number to be detected.