This article describes some health effects of drinking coffee. Among the key findings were (a) women who drank four or more cups a day reduced their risk of endometrial cancer by 25% compared with those who drank less than one cup a day and (b) men who drank six or more cups had a 60% lower risk of developing the most deadly form of prostate cancer than those who drank less than one cup a day.

What do you think?

What is the technical term for the measure of risk reduction reported? What measures of risk reduction cannot be determined from the article? What additional information would have been helpful for assessing risk reduction?

This is called the "relative risk reduction." The article does not provide information necessary to compute the absolute risk reduction, the odds ratio, or the number needed to treat. It would have been helpful if the article had reported the proportion of women drinking less than one cup a day who developed endometrial cancer as well as the analogous statistic for men and prostate cancer.