Posted by admin | Posted in Herbs Botanicals | Posted on 15-05-2009
Tags: a, antioxidant, beta-carotene, ginkgo_biloba, health, nutrition, research
Statistics question.........Please help!?
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 pple 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.
a) what are the explanatory and response variables in this experiment?
b) The study was double-blind. what does this mean?
c) What does "no significant difference" mean in describing the outcome of the study?
d) Suggest some lurking variables that could explain why pple 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.
a) Explanatory variables are the ones you are testing to see if they will "explain" a certain response. In this case those are "daily beta-carotene, daily vitamins C and E, all three vitamins every day." Response variables are the responses you are measuring. Here, that would be the incidence of colon cancer in the study patients.
b) Double blind means neither the patients, nor the researches knows which of the treatments each of the patients is given until the end of the study.
c) There will always be some random variation in responses. No significant response means that the differences in responses are not great enough to be confident that the differences were not caused by simple random variation.
d) One lurking variable might be the significant amount of fiber in many fruits and vegetables. Perhaps the reason people who eat lots of fruits and vegetables have a lower occurrence of colon cancer because of a higher fiber intake, rather than the vitamins.
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