You Have Been Asked to Review and Summarize Three Experiments

question 73

Essay

You have been asked to review and summarize three experiments regarding caffeine consumption and cancer.
A. In experiment A, researchers looked at the incidence of colon cancer among 100 regular tea drinkers and 100 non-tea drinkers in Japan, all between the ages of 18 and 38, and found that tea drinkers had less colon cancer than non-tea drinkers.
B. In experiment B, researchers looked at the incidence of pancreatic cancer among 300 heavy drinkers of yerba mate (Ilex paraguensis, a tree whose leaves and stems contain high levels of caffeine), 300 moderate yerba mate drinkers, and 300 non-yerba mate drinkers in Argentina, all between the ages of 40 and 60. This study showed that heavy yerba mate drinkers had higher levels of pancreatic cancer than moderate yerba mate drinkers, and moderate yerba mate drinkers had higher levels than non-drinkers.
C. In experiment C, researchers looked at the levels of prostate cancer among men ages 40 to 80 in the United States. The study examined 1000 coffee drinkers and 1000 non-coffee drinkers and found slightly lower levels of prostate cancer among the coffee-drinking men.
How do you summarize and reconcile these three experiments that have varying results with respect to the relationship between caffeine and cancer? Are some of them wrong?

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Definitions:

Dollar Depreciated

A decrease in the value of the United States dollar compared to other currencies, lowering its buying power.

Yen

The official currency of Japan, known internationally by its symbol ¥ and used extensively both domestically and in international finance.

Trade Surplus

A situation where the value of a country's exports exceeds the value of its imports.

Exchange Rate

The value of one currency for the purpose of conversion to another, indicating how much one currency is worth in terms of another.