Question

Suppose there is a test for esophageal cancer that is 95% accurate both on those that do and those that do not have esophageal cancer. if 0.7 percent of the population has esophageal cancer, compute the probability that a person has this cancer, given that his or her test results indicates so.

Answer 1

It was already stated that the probability that the population may have esophageal cancer is 0.7 percent. However, the additional statement that the accuracy is 95% will affect the probability as follows:

Probability = (0.007)(0.95) = 0.00665 or 0.665%

So instead of 0.7%, the probability will decreased to 0.665% because of the accuracy.