Question

Numerical example of screening for breast cancer

Let’s work with some numbers in connection with extensive and intensive margin using the screening example mentioned in the book. Let’s assume that p, probability of detecting true cases, is 0.9; q, probability of a false positive, is 0.05; f, probability of true positives in the population, is 0.2.

1. Consider the initial population of 1,000, what is the yield (total number of detection)?
2. Now, suppose that we extend the screening to a new population of 1,000 woman with younger age, whose f is only 0.1 (less of them would have breast cancer). Calculate the additional yield. What is the extensive margin?
3. Go back to case a) with the original population, suppose now we can increase p to 0.95 by screening women more frequently, at a price of a higher q of 0.1. What is total yield now? What is the intensive margin?

Answer 1