Researchers investigated the possible beneficial effect on heart health of drinking black tea and whether adding milk to the tea reduces any possible benefit. Twenty-four volunteers were randomly assigned to one of three groups. Every day for a month, participants in group 1 drank two cups of hot black tea without milk, participants in group 2 drank two cups of hot black tea with milk, and participants in group 3 drank two cups of hot water but no tea. At the end of the month, the researchers measured the change in each of the participants’ heart health. Did the researchers conduct an experiment or an observational study? Explain. Why did the researchers include a group who drank hot water but no tea? Is it reasonable to generalize the results of the study beyond the 24 participants? Explain why or why not.
Researchers investigated the possible beneficial effect on heart health of drinking black tea and whether adding milk to the tea reduces any possible benefit. Twenty-four volunteers were randomly assigned to one of three groups. Every day for a month, participants in group 1 drank two cups of hot black tea without milk, participants in group 2 drank two cups of hot black tea with milk, and participants in group 3 drank two cups of hot water but no tea. At the end of the month, the researchers measured the change in each of the participants’ heart health.
Did the researchers conduct an experiment or an observational study? Explain.
Why did the researchers include a group who drank hot water but no tea?
Is it reasonable to generalize the results of the study beyond the 24 participants? Explain why or why not.
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