For women who develop breast cancer the test is negative 2 percent of the time. What is the probability that the test is positive given cancer?

1. Inside the group of women with cancer, the test is either negative or positive. 2. Those two conditional probabilities are complements and must add to one. 3. So the positive conditional is 1 minus 0.02, which is 0.98. 4. The value 0.15 is the probability of a positive test in the general population and answers a different question. _Source: OpenStax Introductory Business Statistics (CC BY 4.0), Ch 3 "Probability Topics", section 3.3 Two Basic Rules of Probability_