Chapter 1.4, Problem 17E

Bias. In each of Exercises 17–20, identify and explain at least one source of bias in the study described. Then suggest how the bias might have been avoided.

17. Healthy Chocolate. The New York Times published an article that included a statement that chocolate “moves toward its rightful place in the food pyramid, somewhere in the high-tone neighborhood of red wine, fruits and vegetables, and green tea.” It was noted that studies showed that eating chocolate was associated with increased levels of antioxidants in blood and that chocolate flavonoids, which are antioxidants, have been associated with decreased risk of heart disease and stroke. Mars Inc. (the candy company) and the Chocolate Manufacturers Association financed much of the research.