In Problem 2.3, we concluded that female lung cancer rates were related to male lung cancer rates in different countries and that breathing secondhand smoke increased the risk of getting breast...

In Problem 2.3, we concluded that female lung cancer rates were related to male lung cancer rates in different countries and that breathing secondhand smoke increased the risk of getting breast cancer. It is also known that breast cancer rates vary with the amount of animal fat in the diet of different countries, an older and more accepted result than the conclusion about involuntary smoking. Until recently, when the tobacco industry began invading developing countries to compensate for declining sales in the developed countries, both high animal fat diets and smoking were more prevalent in richer countries than poorer ones. This fact could mean that the dependence of female breast cancer rates on male lung cancer rates we discovered in Problem 2.3 is really an artifact of the fact that diet and smoking are changing together, so that the effects are confounded. A. Taking the effect of dietary animal fat into account, does the breast cancer rate remain dependent on the male lung cancer rate? B. Is there an interaction between the effects of diet and exposure to secondhand smoke on the breast cancer rate? The data are in Table D-2, Appendix D.

Table D-2