A colonoscopy is a screening test for colon cancer, recommended as a routine test for adults over age . One study1 provides the best evidence yet that this test saves lives. The proportion of people with colon polyps expected to die from colon cancer is . A sample of people who had polyps removed during a colonoscopy were followed for years, and of them died from colon cancer. Does this provide evidence that the proportion of people who die from colon cancer after having polyps removed in a colonoscopy is significantly less than the expected proportion (without a colonoscopy) of: