What Is Life? 2nd Edition by Jay Phelan

Exercise 15

Lately there have been many claims concerning the health benefits of green tea. Suppose you read a claim that alleges drinking green tea causes weight loss. You are provided with the following information about the studies that led to this claim. People were weighed at the beginning of the study. People were asked to drink two cups of green tea every day for 6 weeks. People were weighed at the end of the study. People who drank green tea for 6 weeks lost some weight by the end of the study. It was concluded that green tea is helpful for weight loss. This study obviously had some holes in its design. Assuming no information other than that provided above, indicate at least four things that could be done to improve the experimental design.