People who eat losts 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 experiemtn divided subjects into four gruops:daily beta-carotene, daily vitamins C and E, all three vitamins every day or daily placebo.
1. What are the explanatory and response variables in this experiment?
My question: Is the placebo considered an explanatory variable??
I know the beta-carotene, vitaminds C and E, and all three vitamins are. The response is the incidence of colon cancer.
In this medical experiment, the explanatory variables are the different treatments given to the subjects: daily beta-carotene, daily vitamins C and E, all three vitamins every day, and daily placebo. The response variable is the incidence of colon cancer.
To answer your question, the placebo is not considered an explanatory variable. In a study, the placebo is often used as a control group to assess the effectiveness of the active treatments. In this case, the placebo would serve as a baseline comparison to determine if the daily intake of beta-carotene or vitamins C and E, or all three vitamins, have any impact on the incidence of colon cancer. The main purpose of the placebo is to account for any potential confounding factors and to establish a comparison for evaluating the effects of the active treatments.