Entropy is a measure of uncertainty

Suppose you are talking with three patients in the waiting room of a doctor's office. All three of them have just completed a medical test which, after some processing, yields one of two possible results: the disease is either present or absent. Let's assume we are dealing with curious and data-oriented individuals. They've researched the probabilities for their specific risk profiles in advance and are now eager to find out the result. Patient A knows that, statistically, there is a 95% chance that he has the disease in question.