High School

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.

a. Did the researchers conduct an experiment or an observational study? Explain.

b. Why did the researchers include a group who drank hot water but no tea?

c. Is it reasonable to generalize the results of the study beyond the 24 participants? Explain why or why not.

Answer :

Final answer:

In the research, an experiment was conducted where the participants' beverage intake was manipulated, and the impact on heart health was measured. A control group was included to compare the effects of tea to water only. Possible generalizations from the study have limitations due to its small sample size.

Explanation:

a. The researchers conducted an experiment because they actively manipulated an aspect of the participants' life (their beverage intake) and then measured the outcome (changes in heart health). In observational studies, researchers observe and record data without intervention.

b. The researchers included a group who drank hot water but no tea as a control group. This helps identify if the black tea (with or without milk) has any effect on heart health relative to just hot water. It's a key components of experimental design that allows researchers to isolate the effects of the independent variable (in this case, tea).

c. The generalization of results beyond the 24 participants can be uncertain due to sample size. It would be more reasonable to generalize the results if the study had a larger, more diverse sample size. However, the study's results can still contribute valuable insights into the potential health benefits of black tea.

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Final answer:

The researchers conducted an experiment, including a control group, and using a small sample size.

Explanation:

a. The researchers conducted an experiment. An experiment involves manipulating variables and observing the effects, which is what the researchers did by assigning participants to different groups and controlling their tea-drinking habits.

b. The researchers included a group who drank hot water but no tea as a control group. The control group provides a baseline for comparison, allowing the researchers to determine if any changes in heart health were specifically due to drinking tea.

c. It is not reasonable to generalize the results of the study beyond the 24 participants. The sample size is too small to draw broad conclusions about the general population's heart health and the effects of tea drinking.

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