Mammograms. A 9-year study in Sweden compared 21,088 women who had mammograms with 21,195 who did not. Of the women who underwent screening, 63 died of breast cancer, compared to 66 deaths among the control group. (The New York Times, Dec 9, 2001)
.a) Do these results support the effectiveness of regular mammograms in preventing deaths from breast cancer?
b) If your conclusion is incorrect, what kind of error have you committed?