"Study Says Coffee May Reduce Risk of Liver Disease" was a headline that appeared in USA Today. This conclusion
was based on data from 494,000 people in the UK Biobank, a biomedical database. The study monitored participants'
liver health over an 11-year period and found that coffee drinkers were 21% less likely to develop chronic liver disease and 49% less likely to die of chronic liver disease than non-coffee drinkers.
1. Based on this study, is it reasonable to conclude that drinking coffee causes lower risk of liver disease? Explain.
(a) Yes, because the sample is large enough to draw conclusions from.
(b) Yes. This was an observational study, but because it followed the same participants over time the
conclusion is reasonable.
(c) Yes, this was an experiment so it is reasonable to conclude that drinking coffee can lower risk of liver
disease.
(d) No, this was an observational study, so cause-and-effect conclusions cannot be drawn.
2. Is it reasonable to generalize the results of this study to all American adults? Explain why or why not.
(a) Yes, the UK has a similar culture and demographic distribution to the United States so it should be
reasonable to generalize the results.
(b) Yes, because some the data would have come from American adults living in the UK.
(c) No, because this data came from people in the UK and not from Americans.
(d) No, because it is unclear whether all the participants were adults when the study began or not.
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1) d. No, this was an observational study, so cause-and-effect conclusions cannot be drawn.
2) c. No, because this data came from people in the UK and not from Americans.
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1. The correct answer is (b) Yes. This was an observational study, but because it followed the same participants over time, the conclusion is reasonable. Observational studies cannot establish causation, but the study design of monitoring the participants' liver health over an 11-year period provides strong evidence for an association between drinking coffee and a lower risk of liver disease.
2. The correct answer is (c) No, because this data came from people in the UK and not from Americans. The study specifically used data from the UK Biobank, so the results are specific to the population in the UK. Differences in culture, lifestyle, genetics, and other factors may affect the generalizability of the results to American adults.