A study reported in the May 17, 2012, issue of The New England Journal of Medicine followed people for an average of 13 years and found that people who consumed two or more cups of coffee a day were less likely to die during the course of the study than those who drank no coffee.
a. Was this study a randomized experiment or an observational study? Explain how you know.
b. Based on this study, can it be concluded that drinking coffee causes people to live longer?
c. The following headlines appeared on news websites reporting these results. In each case, explain whether or not the conclusion in the headline is justified.
i. “Coffee positively associated with life expectancy” (Source:www.coffeeandhealth.org/2012/05/21/coffee-positively-associated-with-life-expectancy/)
ii. “NIH Study: Coffee Really Does Make You Live Longer, After All” (Source:www.theatlantic.com/health/archive/2012/05/nih-study-coffee-re-ally-does-make-you-live-longer-after-all/257302/)