A 30-year study was conducted with nearly 90,000 female participants.8 During a 5-year screening period, each woman was randomized to one of two groups: in the first group, women received regular mammograms to screen for breast cancer, and in the second group, women received regular non-mammogram breast cancer exams. No intervention was made during the following 25 years of the study, and we’ll consider death resulting from breast cancer over the full 30-year period. Results from the study are summarized in the table. If mammograms are much more effective than non-mammogram breast cancer exams, then we would expect to see additional deaths from breast cancer in the control group. On the other hand, if mammograms are not as effective as regular breast cancer exams, we would expect to see an increase in breast cancer deaths in the mammogram group.
yes | no | |
mammogram | 500 | 44,425 |
control | 505 | 44,405 |
a.)Is this study an experiment or an observational study?
b) Set up hypotheses to test whether there was a difference in breast cancer deaths in the mammogram and control groups.
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