Bayes’s Theorem calculates the probability of an event based upon the conditions that might be relevant to the event and is widely used to test the precision of medical tests and drugs efficacy.
Simon explains Bayes’ Theorem to Dad. To illustrate the theorem, he loves using the math riddle he first saw on the Veritasium channel, about someone getting positive results on a rare disease test: The test has a precision rate of 99% and it is also known that the disease occurrence rate is 1/1000. What is the probability that the person tested positively really has the disease? (Answer: 11/1000 or 9%).