5.87 Screening smokers for lung cancer An article about using a diagnostic test (helical computed tomography) to screen adult smokers for lung cancer warned that a negative test may cause harm by providing smokers with false reassurance, and a false-positive test results in an unnecessary operation opening the smoker’s chest (Mahadevia et al., JAMA, vol. 289, pp. 313–322, 2003). Explain what false negatives and false positives mean in the context of this diagnostic test.