Case-control study

      Define the term case-control study, describing how cases and controls are selected. Compare and contrast case-cross control studies with respect to their specific applications. Using the textbook, list some examples of case-control and cross-sectional studies. Describe the advantages and disadvantages of each of the following types of controls in a case-control study: Population-based Hospital cases Relatives The association between job-related exposure to welding fumes and chronic obstructive pulmonary disease (COPD) was explored in a case-control study. The following data were reported for 399 COPD patients: 37 currently employed as welders; the remainder had no occupational exposure. Among 800 controls, 48 were employed as welders. Set up a 2 by 2 table and calculate the OR (odds ratio) between welding and COPD. Why would you exclude women who cannot develop the disease as controls in a case-control study of gynecologic cancer?