Consider when you are listening to a new patient who says they have had a fever for 3 days. You would use your knowledge and experience with probability to come to a diagnosis. What changes those probabilities? Is it age, is it other symptoms, is it new study results? What is the source of these probabilities and what causes these probabilities to change? This discussion is not to debate diagnoses, but to focus on the sources and influences on probabilities.
Holmes, A., Illowsky, B., & Dean, S. (2018). Introductory Business Statistics. Houston, Texas: Rice University.