In a National Cancer Institute study of the potential benefits of breast self-exams, 226,064 Chinese women in Shanghai were randomly assigned to a breast self-exam instruction group (132,979 women) or a control group (133,085 women). Over the next 10 to 11 years, there were 131 breast cancer deaths in the self-exam group, and 135 breast cancer deaths in the control group. The authors concluded that intensive instruction in breast self-exam did not reduce mortality from breast cancer.. What were the rates of breast cancer deaths in the two groups per 100,000 women?
Question 2
The next three questions are based on a study (part of the Women's Health Initiative) of healthy women volunteers. A total of 16,608 women were randomly assigned to take either placebo or a popular hormone replacement therapy (HRT) for eight years. The study was stopped after 5 years in part because the women on HRT had a higher rate of heart attacks than the placebo group. The rate of invasive breast cancer was 30 per 10,000 women in the placebo group and 38 per 10,000 women in the HRT group. What was the increase in the rate of breast cancers in the HRT group compared to the rate in the placebo group?
A field study of guppy life history evolution.