People who eat lots of fruits and vegetables have lower rates of colon cancer than those who eat little of these foods. Fruits and vegetables are rich in "antioxidants" such as vitamins A, C, and E. Will taking antioxidants help prevent colon cancer?
A medical experiment studied this question with 864 people who were at risk of colon cancer. The subjects were divided into four groups: daily beta-carotene, daily vitamins C and E, all three vitamins every day, or daily placebo. After four years, the researchers were surprised to find no significant difference in colon cancer among the groups.
- Explain what sampling method and experimental design you would use to conduct such research.
- What do you think "no significant difference" means in describing the outcome of the study?
- Suggest some lurking variables that could explain why people who eat lots of fruits and vegetables have lower rates of colon cancer. (The experiment suggests that these variables, rather than the antioxidants, may be responsible for the observed benefits of fruits and vegetables.
Answer only needs to be minimum 250 words, nothing fancy like graphs or anything just words.