For Questions Use the Following Narrative

Essay

For Questions use the following narrative
Narrative: BMD
A recent magazine article stated that bone mineral density (BMD) may one day predict breast cancer risk in older women, according to a study in the Journal of the National Cancer Institute.Researchers followed the health of 8,905 women who were 65 or older and initially cancer free.Eventually 315 participants developed breast cancer.Women with the highest BMD were almost three times more likely to develop breast cancer, compared to the women with low BMD.(Better Homes and Gardens, October 2001, page 224.)
-{BMD Narrative} Explain why it is not possible to conduct a randomized experiment in this situation.