Chapter 5.A, Problem 36E

Type of Study. Determine whether the following studies are observational studies or experiments. If the study is an experiment, identify the control and treatment groups, and discuss whether single-or double-blinding is necessary. If the study is observational, state whether it is a case-control study, and if so, identify the cases and controls.

36. A National Cancer Institute study of 716 melanoma patients and 1014 cancer-free patients matched by age, sex, and race found that those having a single large mole had twice the risk of melanoma. Having 10 or more moles was associated with a 12 times greater risk of melanoma (Journal of the American Medical Association).