A case-control study claimed to have found a relationship between drinking coffee and pancreatic cancer. The cases were people recently hospitalized with pancreatic cancer, and the controls were people hospitalized for other reasons. When asked about their coffee consumption for the past year, it was found that the cancer cases drank more coffee than the controls.
a. Draw a picture illustrating how this study was done, similar to Figure 5.3 on page 106.
b. Give a reasonable explanation for this difference in coffee consumption, other than the possibility that drinking coffee causes pancreatic cancer.