Researchers investigated the possible beneficial effect on heart health of drink
ID: 3158039 • Letter: R
Question
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 I drank two cups of hot black tea w 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.Explanation / Answer
24 volunteers are randonly selected to one of the three groups.
Group I drinks two cups of hot black tea without milk
Group II drinks two cups of hot black tea with milk
Group III drinks two cups of hot water but no tea.
At the end of the month, the researchers measured the change in each of the participant's heart health.
The average change of health status of three Groups can be measured and let it be X1', X2' and X3'. We can set up the hypothesis of no difference of heart health i.e H0 : µ1 = µ2 = µ3 against the alternative hypothesis that they are not equal. As the sample size is less than 30, we can use t-statistic.
Under the above logic, (a) it is an experiment.
(b) Group III has been tested to compare the effect of tea or to have comparison between GroupI and Group III.
(c) Yes it can be generated by using the normal distriution for more than 30 sample using the Central Limit Theorem.
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